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FAQs on the Molly Behavior

Related Articles: Mollies, & Poeciliids: Guppies, Platies, Swordtails, Mollies by Neale Monks, Livebearing Fishes by Bob Fenner,

Related FAQs: Mollies 1, Mollies 2, Molly Identification FAQs, Molly Compatibility FAQs, Molly Selection FAQs, Molly System FAQs, Molly Feeding FAQs, Molly Disease FAQs, Molly Reproduction FAQs, Livebearers, Guppies, Platies, Swordtails

Mollie needs help PLEASE? Beh., stkg.      10/29/18
So I've had my Dalmatian since May. My favorite of all. My male black Mollie CONSTANTLY harasses her since June.
<Mmm; yes; this is "what they do"; hence the need for stocking more females than males, having decor they can hide, evade each other, space to get away>
She just had fry last week. Since her spine is all bent and keeps swimming weird. I moved her to my other tank (no males just a community Betta and a couple guppies) but is she sick or is this normal?
<Likely normal>
Took black stallion months to even get her pregnant of constant harassment. I don't want to lose her. I can send pic or video if that would help. Thanks in advance.
<Add more females if you have room; more floating plants... perhaps watersprite/Ceratopteris. Bob Fenner>

Mollie needs help PLEASE? /Neale       11/1/18
So I've had my Dalmatian since May. My favorite of all. My male black Mollie CONSTANTLY harasses her since June.
<It is what the males do. Ideally, keep 2-3 females per male, and even better if you can add some salt-tolerant floating plants to help her hide at times, such as Floating Indian Fern.>
She just had fry last week. Since her spine is all bent and keeps swimming weird. I moved her to my other tank (no males just a community Betta and a couple guppies) but is she sick or is this normal?
<Not normal.>
Took black stallion months to even get her pregnant of constant harassment.
<It's very unusual for female Mollies (kept with males) to *not* be pregnant, and much more likely that any fry were eaten by other fish before you see them. But yes, harassment can cause them to miscarry on occasion.
See above with regard to tips that can help.>
I don't want to lose her.
<Do review the basics.
Mollies appreciate warmth, hard water, a plant-based diet, and a bit of salt added to the water. In fact they'll thrive in seawater, but often become sickly in plain freshwater, and adding a scant teaspoon (around 5 grams) of aquarium 'tonic' salt or even better marine salt mix per litre of water can make a huge difference. That's about two-thirds of an ounce per US gallon.>
I can send pic or video if that would help. Thanks in advance.
<Hope this helps, Neale.>

Re: Mollie needs help PLEASE?       11/1/18
My aquariums are in excellent status to suit Mollies and all levels of nitrites, nitrates, ammonia, pH are all great
<Actual values would mean a lot more to me than this statement, I'm afraid. What's "excellent" for Bettas is actually "terrible" for Mollies. So it's one, or the other, but can't be both. Kind of like saying you're keeping both Camels and Polar Bears in the same excellent environment. Can't possibly be true. Make sense?><<Does to me; excellent allusion/comparison. B>>
and have been for months and there are a total of 5 females (1 Dalmatian and 4 white) to one male (black). I always use aquarium salt when cleaning and pre-prepping new water.
<How much? Depending on the hardness and pH of your tap water, more or less salt would be helpful. If you have very hard, alkaline water -- i.e., around 20 degrees dH, pH 8 -- then you might not need much salt at all. But if you had soft water -- <10 degrees dH, <pH 7 -- then a sizeable quantity of salt would be essential for Mollies to survive any great length of time.>
I never just add tap water.
Tanks always crystal clear. Seems like she gave birth and then ended up like this the next morning and hasn't changed since. She is the only one having an issue I see that way however I noticed the top dorsal fin on Midnight (black Mollie) and Pearl (2 of the white ones) brown tint spots rather than his black and her white and I used my lens to zoom in and almost looks as if my bristle nose looks to be almost beginning to peel. Maybe too much salt?
<For the Mollies, no; for the other fish, could easily be. Salt SHOULD NOT be used in standard community tanks except for treating specific illnesses. Put another way, a "safe" level of salt for Bettas and Bristlenose Catfish will have no, as in ZERO, helpful effect on your Mollies. The idea of using "tonic salt" in community tanks goes back decades, and some aquarium shops still sell the stuff, even though it's been debunked since at least the 1980s.>
I even have a community Betta and all seem happy but the Dalmatian (Spinky).
<Do please read the article I sent you last time. Mollies are NOT community fish, and attempts to keep them thus usually have mixed results, at best. Some live, some die, but hardly anyone gets all the Mollies they bought to live long, normal lives in plain vanilla community tanks.>
I test my water after every cleaning, liquid test kit not strips,
<So again, please share the values, not your interpretations.>
and I never do the filter on the same day
I usually give 2 days between cleaning tank and cleaning filter.
<I'd even leave a week, but sure, this is fine.>
I have noticed a wee hint of stinky fish odor.
<Often normal. Could be decaying fish food around the hood/edges of the tank.>
But I was able to capture 12 of her babies in a breeder net.
Thx for any and all other advice. Maybe the only thing different I've done recently was add drift wood and feeding zucchini to my albino algae eaters and Bristlenose buddy and my zebra algae eaters in my other tank but the other tank seems fine. I did soak the drift wood (purchased at an actual fish store not just a pet store) for about 7 days plus boiled prior and let cool before adding. Thanks in advance.
<The Molly with the white gunk is showing the classic 'something wrong, but hard to say what' scenario you see with livebearers generally. It may be a parasite called Costia (also known as Slime Disease) but often seems to be environmental. High nitrate can be a cause, especially with Mollies, which in freshwater rarely tolerate above 20 mg/l nitrate before showing a tendency towards disease. Read, review your tank, and act accordingly.
Cheers, Neale.>
Re: Mollie needs help PLEASE?       11/1/18

Okay, thank you. Nitrates 0 ppm,
<I find that hard to believe unless you have rampant plant growth (i.e., removing armfuls of plants per week) and minimal stocking. Nitrate is the end product of the biological filtration process. It goes nowhere. So should accumulate between water changes. If it doesn't increase above tap water levels, then either there's no biological filtration going on, or your test kit is broken. Tap water supplies typically have somewhere between 10-40 mg/l, depending on your supplier, so again, zero levels even for freshly drawn tap water are extremely unusual.>
Nitrites 0 ppm, ammonia 0 ppm,
pH around 7.6-7.8 if that helps.
<Good for Mollies; less good for Bettas and Bristlenose Cats. You don't mention how much salt you add. Likely adding more (which would stress/kill the Betta) would be a very good first step in the sick Molly's recovery.>
Both tanks. My tank with the Betta she is solely with guppies and mollies are in their own tank.
<Understood. Regardless, Bettas and Mollies aren't really compatible for the reasons described earlier. Mollies are best kept with Mollies, Mollies, or some other type of Molly. Being slightly flippant there, but their need for relatively warm water, brisk water currents, plant-based diet, hard water chemistry, and realistically, the option to add significant salinity, all make them tricky to house with anything other than fish from similar habitats. Some coastal Killifish species can work, like Florida Flags, and some of the gobies too, Knight Gobies for example, but otherwise Mollies are single-species rather than community tank residents if you want 100% success.>
Thanks again.
<Most welcome. Cheers, Neale.>

Re: Mollie needs help PLEASE?       11/3/18
Well thanks for the education on mollies.
<We aim to please!>
Nitrites are at about the 30 mark
<Do you mean nitrate? Nitrite (with an "i") would be beyond lethal at 30 mg/l. Nitrate (with an "a") at 30 mg/l would be typical tap water, a bit high for Mollies (in freshwater, at least) and most cichlids as well, but acceptable to most other community fish (tetras, catfish, etc.). So fine for general fishkeeping, but not good for Mollies if you insist on keeping them in freshwater conditions.>
but I test after 48 hours of water change so water has time to cycle through biofilter.
<Nitrate will ONLY increase going through a biological filter. By definition that has to be the case, since what a biological filter does is turn toxic ammonia ions into less toxic nitrite ions, and then those less
toxic nitrite ions into almost completely harmless nitrate ions. Nitrate is the end product, so kind of like dirty plates in a restaurant without a dishwasher, as time passes, just as the pile of dirty plates gets taller,
so does the nitrate level in the fish tank go up. Nitrate is, in almost all community tanks, removed (well, diluted at least) through water changes. If your nitrate level is 30 mg/l out of the tap, then that's as low as it can ever go. It'll creep up to 35, 40, 45 mg/l as the weeks pass. Under experimental conditions, nitrate isn't particularly toxic until at least upwards of 100 mg/l, but that's based on work with food fish done in labs.
Some aquarium fish are equally tolerant, but cichlids, Mollies, and most marine fish are much more sensitive. They become sickly as nitrate creeps above 20 mg/l, and above 40 mg/l they often show severe health problems. In the case of Mollies, it's often over-production of mucous that becomes the most obvious thing, together with fin-clamping, rocking from side to side ("the shimmies"), and a tendency towards diseases such as Finrot and Fungus.>
I also use stress zyme plus when needed.
<Let's be clear here. API Stress Coat is a useful product for use when shipping fish or when introducing new livestock that may have been damaged in transit, but otherwise serves no particular benefit above that of plain vanilla water conditioner. So it's nice, but not essential. API Stress Zyme on the other hand is almost completely useless. It may or may not speed up the cycling process, reports are very mixed indeed, but what it doesn't do is magically improve the aquarium once the filter is properly matured. Of
course API will happily sell the stuff, and it probably does no harm, but it doesn't do anything a water change and filter clean won't do better.>
Bettas water is diff than the Molly tank.
<Good oh!>
Thx again. Going to redo something's. And I do have plants in the tanks.
Have a great day and again thx for your time.
<Glad to help. Neale.>

Hyper-Aggressive Male Molly     1/5/17
<Hello Caitlin,>
I've been keeping and raising molly fish for years now, but suddenly two weeks ago the two male mollies I had in my tank started displaying incredibly aggressive behavior towards each other and my (at the time) lone female molly in the tank. She ended up getting pregnant (as mollies do) and the day she gave birth to four or five fry, the two males began fighting each other pretty viciously. Before the fry were born, neither male had ever shown any aggression to one another or any other fish- they were both born in the tank, have lived there in peace for almost three years now- so
it was a shock to see them behaving so out of the ordinary. After reading up about their behavior thanks to the amazing information your website was able to provide, I decided to add in more female mollies (something I was and am reluctant to do as I will likely be moving sometime soon, and I didn't want to have to move so many fish over four hours up the road) but when I did add the new females in, a larger Dalmatian molly and two smaller gold dusts, one of the male mollies started very viciously attacking the two smaller gold dust mollies to the point where I was sure he was going to
kill them.
<Understood. When adding extra fish to the system, there's a "getting to know you" period where existing fish jostle for position with the newcomers, establishing a pecking order. It can help to remove pre-existing territorial Mollies, rearrange rocks and plants so the tank looks new, introduce the new Mollies, turn out the lights, and an hour later, add the original Mollies. With luck, the tank will look new to all the Mollies, the lights being out will trick them into sleepy time, and by the next morning, peace will reign. Doesn't always work, but it often does.>
Taking more advice from WWM, I put him in an emergency backup tank for three days to try and get him to calm down (the only breeding box I have is being used for the recent fry), but when he was reintroduced to the tank he immediately began attacking the two smaller females again and fighting with the other male. I pulled him back out into timeout for the safety of all involved, but I'm really not sure what else I can do to keep him from attacking the two gold dust females.
<See above; if that fails, can you rehome him?>
He completely ignores the other two bigger female mollies in the tank, and when he attacks the gold dusts it doesn't seem to be with any mating intent; he often pins one against the bottom or side of the tank and, for lack of a description, seems to spasm and body slam them into the gravel and tank walls or bites at their sides and tails when they flinch or try
and run away, though he never seems to be trying to mate with them because his anal fin never moves to "do the deed", as it were. The tank itself is 33 gallons, with a pH level of 7.5, nitrite and nitrate at slightly above zero (though I'll be doing a water change and cleaning almost immediately after I send this question), with no traces of chlorine and fairly high hardness and alkalinity. There are three other fish in my tank: one Glass Catfish, one Zebra Danio (both of which are only alone because I received the glass catfish from a neighbor who was moving and only had the one left,
and the zebra Danio is the last survivor of five- they're actually almost ten years old, now), and one Chinese Algae Eater (who, after reading up on them on your website, I may not have for much longer. Didn't do my research on that one). Do you have any other advice for calming a male molly's aggression, or any ideas why both males so suddenly became aggressive? I'm thinking of upping the female-to-male ratio to 3:1, as it likely should be, but I don't want to add more females into the tank if he's going to ignore them, like the others, and just focus on the two gold dusts again. The
other male in my tank displays none of the killing-aggression of the one I removed, and everything calmed down very quickly after I pulled out the problem one. I really wouldn't want to get rid of him, but I'd like to know if there's any hope of returning him to my main tank or if I should go shopping for another. Thank you for any help you can provide! -- Cj
<Hope this helps, Neale.>

Male Mollie aggression        12/16/15
I have a 50 litre warm water tank with a few different kinds of fish Including orange mollies, white mollies, an eel, and 7 angel fish.
<Yikes.... not compatible in terms of environment really. Mollies need hard, alkaline water; often with a modicum of salts added. Angels require warmer, soft, acidic water sans salts>

I use to have two black mollies one male and one female as I have one male white Mollie and one female white Mollie and they all seemed to me getting along just fine. I had them for about 3 months but recently it Seems my white
female Is pregnant. After noticing this after a few days my black male Mollie died suddenly over night with no signs of illness. And a few days later my black female died. I decided to get a new pair of orange mollies but when I put them In the tank my white male seemed to attack them causing them to hide. I took my white male out after this and also because he would not give my white female a break.
<Common w/ many livebearers... esp. Poeciliids... reason for stocking more females than males, granting them plenty of space, habitat>

I put him back into the tank two days later in hopes that the aggression would subside but he ended up taking off
My orange female mollies left side fin. I'm not sure what to do as I would be very torn to get rid of any of my mollies. I have been working with aquariums for 4 years now and have not seen this before. Please provide me with any information on what could be causing this and how I could stop it.
Thanks so much!
<I'd give the aggressive male a few more days of "time out" in a floating plastic colander, fish trap; what have you, in the tank; and look into getting more females. See WWM re Mollienesia compatibility and stocking.
Bob Fenner>

Flashing molly. Env., using WWM      9/13/13
I have  a 2 month old  29 gallon tank cycled for 3 weeks  with CaribSea  media containing bacteria. (fish food  added  to  feed  bacteria). Added 4 neons,
<Stop: Mollies and Neons (tetras) are not compatible... water quality nor temperament wise.
See WWM re both, all species>
 after 2 weeks 3 lyre tail Dalmatian mollies, 4 more neons and 2 Corydoras.
Only learned now  the  need  for  brackish water for mollies which I can't address because  of  the  other  fish in the  tank.
<Ah yes>
My question is that I  see  the mollies flashing occasionally,
<Likely the water quality issue you've just mentioned; but do "flash" some naturally.
Again, just search, read on WWM re their systems... NEED hard, alkaline, cooler, often salty water>
usually against plants especially the pregnant one. If  I  watch  for 30 minutes it  will  flash 1-2 times. I see  nothing  on  their bodies  that  looks like  Ich and  they  seem  active  and  happy, feeding, playing  grazing on plants. I started  treatment with Jungle Ich
<Stop again: The real issue here won't be solved by pouring in "medicines"... The environment has to be fixed>
 clear following  directions for 2  days  now. Still nothing  on  their  skin that I can see (they  are  mostly white) or  on the  other  fish.
Raised  temp to 80.  Still look active and  healthy to me. Is  this  flashing possibly  just normal behavior? I saw  the  Corydoras do it  2  times, never the neons.
<... Read on! Use the search tool, on every page on WWM. Bob Fenner>
Re: Flashing molly.     9/13/13

I am sorry , I should have mentioned that i have checked the  water quality couple of times these past  week. No nitrates or nitrite, chlorine, pH 7.2, total alkalinity 80 (moderate), hardness 75ppm.
<Good; and no ammonia I take it. BobF>
Re: Flashing molly.

The neons and mollies just ignore each other to my eye.
<... they'll soon be dead if not accommodated. READ where you've been referred. B>
Re: Flashing molly.
So this behavior is not "normal". It indicates something?
<Read, don't write. B>
Re: Flashing molly.

I have read and read for 1 week now. It is because of reading I started the medication. What should I read on WWM. Thank you for your help.
and the linked files above
Re: Flashing molly.     9/13/13

my test doesn't have ammonia

Do male Mollies "mark" territory?     6/12/13
I have a 29 gallon aquarium with 5 Dalmatian mollies, 2 danios (GloFish), and 2 still small Plecos.
<Do check re what genus, species these last are. Some sold in the trade get VERY large>
  Occasionally, one of the bigger male mollies will chase the smaller male, although sometimes turnabout is fair play, and I catch the smaller one creeping up on the other to play chase.
<Normal behavior>
  Occasionally, they circle each other, and then go their separate ways. 
When this is occurring, however, I will see one, sometimes both, "flash" against something.  I only ever see them flash during this activity.  None of the others flash against objects.  Could this be something different than a disease process?
<Might well be. Fishes do "flash" against objects for seemingly no reason at times>
 I see no obvious signs of any parasite, and my parameters are good, though my nitrates crept up after a filter change. 
<NO3, other metabolite accumulation is positively correlated w/ scratching behavior>
I did PWC until they were back down ( though the nitrate reading wasn't near danger levels, just higher than usual).  Just curious.
<Don't really know... but interesting to speculate for sure. Perhaps some folk on the various livebearer oriented bb's may have more. Bob Fenner>

Male Mollies an over breeding, beh., stkg...     4/1/13
So my husband and I have had a fish tank for the last 7 years and we have always chosen to get Mollies as they are beautiful fish, are rather hearty (we have had some females live to be 3 years old), easy to care for, tend to have fry that could survive getting eaten (had one family last seven generations), and usually last a long time...
<Ahh, you likely have "good molly water" (hard and alkaline), have kept the water not too warm, well-cycled, regularly maintained through water changes....>
 We also have them in a tank with one large (5 year old) gourami, danios, a couple platies and two tiger barbs (not friendly fish but they have adapted well...) At first we would always get a pair, one male and one female. We learned very quickly that the males can be very aggressive and actually (for lack of better terms) rape the females to death... Is this what is truly happening to our fish?
<Can be trouble>
We can tell that the females are already pregnant and have been very successful in keeping them and their fry alive but more often than not the males will constantly chase the females around and try to mate with them, even
after they are pregnant. We just bought some more fish because our population was getting low and now have two orange lyre tail mollies and two silver mollies. We asked for one male and three females
<Good ratio>
but got two of each and now both females are pregnant and both males are still trying to breed with both of them. I have seen this in the past and usually the female will give birth then die... I have had many females give birth and survive, but I am just wondering... Is it possible that our females are getting very stressed out by these males "over matting" with them??
 And if so... do I need to get rid of the males because they are very beautiful fish and I don't want to but I also don't want my females to get over stressed...
<Either that/this or add more females if you have room>
By the way we do normal water changes keeping our ph at about 7.6, use aquarium salt to help all of the fish stay healthy and also regularly change our filter media...
<Ahh, as I suggested above>
 Just hoping for some suggestion because I have put the males in "fishy jail" because they are over breeding with our females, but they males get along together just fine! I just don't want our females to get "raped"...
Help please......
Jeff and Erika
<Cheers, and thank you for sharing. Bob Fenner> 

Orange Molly under observation tremors after eating     8/9/12
Hi all,
Thanks for this great site and the solution of the problems discussed here in detail. 5 months before when we started our new fish aquarium we ended up loosing some 5-6 fishes but then came across this site. This site helped us a lot in maintaining and treating our aquarium. We learnt so much from this site that we were actually able to save our black lyre tail Molly from dropsy. That day it seemed that he is going to die as it was swimming heads-up vertically. Today he is perfectly fine and is the most notorious fish in our tank :).
Well, this time it's something new and we are not able to find a solution.
We have a orange male Molly and some 4 days ago we noticed that at times it is getting vertical under the flow of the filter water current. We also noticed that there is mix of white and red (color of the food ) color poop. Since the white color proportion was more and also he was getting vertical at times - we decided to treat him with Copper Safe and Maracyn 2. Today is its 5th day of the treatment. Meanwhile we fed him peas for two days along with the medication and then started giving him normal flakes. Till yesterday it seemed that things are going fine and that we will be able to put him back in the Aquarium soon. Yesterday -we noticed that as soon as we gave him flakes - it did finish it and then started scratching against the wall. At times it also shook its body as something is bothering him from inside. Since it was its 4th day medication, we were still calm but today again the same thing happened. We did give him less flakes compared to yesterday's amount , yet it behaved the same way. There are no other signs of any problem. He swims perfectly well and eats like anything.
Any suggestion as to what went wrong and then should we really continue putting him under medication. Since its going to be the 5th day - we are worried about him.
Note - he is already in a hospital tank and we are changing 50% of the water everyday and putting up fresh medication as per the mentioned dosage.
Thanks a lot in advance
<Hmm… do start by reading here:
And then have a peruse of this page, plus the subsequent Molly Disease FAQs:
There's something called "the Shimmies" that affects the way Mollies swim. It's said to be neurological, but caused by some shortcoming in the environment. Switching Mollies from a freshwater to a brackish water aquarium may (often does) make all the difference. If that happens with your Molly, then problem solved, and like some (though not all) Mollies, this chap will do better, stay healthier in brackish water. Start by raising the salinity in your hospital tank to 5 grammes marine aquarium salt mix per litre of water; that's about SG 1.003 if you happen to have a hydrometer. Of course brackish water won't be tolerated by most community fish, but since Mollies aren't community fish anyway, and best kept among their own kind, this rarely poses a problem to the serious fishkeeper. By testing the effect of salinity in a hospital tank though, you can see if this'll be the cure before changing the salinity in the main aquarium. Cheers, Neale.>
Re: Orange Molly under observation tremors after eating     8/9/12

Thanks for the prompt reply - we are already using API Aquarium Salt for the Freshwater Fish (again all thanks to WWM) .
<Can we please be clear here -- "aquarium salt" is NOT marine aquarium salt, and it is NOT AS GOOD as using marine aquarium salt! When you buy aquarium salt, what you're getting is overpriced cooking salt without the added iodine (basically, Kosher salt).>
We use 1 table spoon of this salt per 5 Gallons of water.
<Not enough to make this brackish. How to put this? SG 1.002 is 5 grammes/litre, 0.65 oz/US gallon. One US gallon is about 3.75 litres, so we're talking 3.75 x 5 grammes = 18.75 grammes per US gallon. With me so far? (Might want to check my maths!) There is roughly 6 grammes of salt per level teaspoon (check your own spoons using kitchen scales), and 3 teaspoons per level tablespoon, so 18.75 grammes is roughly 3 tablespoons of salt PER US GALLON. In other words, you're dosing one-third as much as would make a difference.>
We have a 20 gallon tank.
<Too small for Mollies. Besides the fact they are big, active fish, the males are aggressive bullies.>
We have put some 1/4 tablespoon of salt in the Hospital Tank too which is a 2 Gallon box/tank.
<Not a long term solution… unlikely to live more than a few days in a tank this tiny.>
Now, should we use Marine Aquarium salt in place of Freshwater Fish salt
<For now, don't worry; use the freshwater salt you have, but up the dosage as described above.>
or should we increase the salt amount in the Hospital tank? We don't have a hydrometer with us.
<Do see above for how to produce useful concentrations.>
And should we continue putting him in Hospital tank ?Is that OK ?
<I would make the main aquarium more salty. You have just Mollies in there?>
<Cheers, Neale.>

Male Molly Behavior    6/6/12
Hello, my name is Janice, and I am fairly new to fishkeeping.
<Welcome to the hobby.>
Aside from having a couple of comet goldfish (that eventually were lost to an over-curious cat) as a child, I haven’t had fish before, and this is my first experience with a “warm water” breed. I don’t think there’s anything specifically wrong, but I’ve been looking around your site for several days now and haven’t seen my particular issue mentioned anywhere. For some background information, my family recently set up a 10 gallon tank (I know now that it’s too small for most fish, but none of us did when we bought it) and decided to try some small colorful fish for it.
<Yes indeed, 10 gallons is too small for most fish, including Guppies and Mollies.>
We tried guppies, and started with four, but had no luck, and they all died. The rest of the family talked to some friends who had had fish, and decided that platies would be good to try.
<On the whole yes, these are the more reliable livebearers for casual aquarists, and while they might survive in 10 gallons, they do honestly need 15+ gallons. Adult female Platies are quite chunky, 5 cm/2 inches.>
I voted for cardinal tetras, as suggested in your article on stocking 5, 10 and 20 gallon tanks, or even getting two or three female Bettas, but was completely outvoted.
<I see.>
So we went to get platies, thinking three or four wouldn’t overcrowd the tank fatally. Once at the pet store, the employee at the fish section recommended we consider mollies, as she’d kept mollies and platies together with no problems for years.
<A bad recommendation for a small tank. Mollies are sensitive to poor water quality, which is a real hazard in small tanks. Plus, Mollies get big (8 cm/3 inches for a small variety, and up to twice that for the big Sailfin Mollies. Do read:
Mollies are easy to buy but difficult to keep.>
Again I was outvoted so we wound up with a Dalmatian lyretail molly, a cremecicle lyretail molly, a Mickey Mouse platy and a sunburst wag platy, all male.
<Oh dear.>
Now for the behavior part. There is some posturing and aggression in the tank, the Dalmatian, as the largest, is uncontested Lord of the tank, and shows particular aggression at feeding time, which I had expected, and don’t worry about, other than watching to make sure each fish does get to eat.
<I see.>
The wag tends to have brief periods of aggression towards the Mickey, but they never last long before they’re swimming off to their preferred areas of the tank, and neither seem overly distressed, or affected for long, so I keep an eye open for torn fins or bloody spots, but don’t worry much otherwise. The odd behavior comes around the middle of the day, when the fish know that they won’t be fed, and are mostly swimming around their favored areas. The Dalmatian has developed a habit of coming up slowly to the cremecicle and sort of nosing around his anal fins. I’m not sure if the Dalmatian is confused and thinks the cremecicle is a female, if the cremecicle is putting out some odd hormonal signals or is hermaphroditic (he definitely has male parts), or if the Dalmatian is just being overly nosy. Is this a behavior I should worry about?
<Mollies will mate indiscriminately -- sperm is, after all, cheap to make -- and any fish that looks vaguely like a female Molly will be mated with. And yes, a male Platy could easily be "mistaken" for a female.>
The cremecicle seems to tolerate it for a while, then when he gets tired of it, goes off and hides in the plants where the Dalmatian doesn’t like to go. will this stress the cremecicle too much?
<Long term, quite probably.>
We are looking at getting a larger tank (likely 20 to 30 gallons), to give them room to spread out and hopefully ease the aggression issues; should we look at getting females for the tank at that point or would the males be fine without any more additions to the tank? Also, unrelated to the previous issue, how long on average do mollies and platies live? I’d like some forewarning on the off chance we do well enough that they wind up making it close to death from age.
Current tank conditions are as follows: Temperature between 76F and 78F (I try to keep it at 77F if possible, they seem the most comfortable at that temp),  pH 6.5 (we’re working on it), Alkalinity 170, GH 75, Nitrate 0, Nitrite 0, and my test kit that includes ammonia levels is still on order.
<Your water is much too soft and acidic for livebearers. At minimum, I'd be adding marine aquarium salt mix at a dosage of about 2-3 grammes/litre. Failing that, read my article on water chemistry, and use the Rift Valley salt mix at about half the recommended dose.
You should aim to harden the water ASAP, and don't for heaven's sake be fooled into buying a pH-up product by your pet store -- hardness and pH are not the same thing! Rift Valley salt mix is infinitely cheaper to make and use, too.>
Many thanks for all your help, and for having such a useful and easy to navigate site, Janice.
<Most welcome, Neale.>

Molly Behaviour   1/15/12
My son recently got his first fish tank and fish and has managed more successfully than expected.  We bought 3 baby fish from our local pet shop about 4 months ago and they were very small less than 1 cm in length and very light in colour. We were told by the shop that they were platies. To be honest we didn't expect them to survive and thought they might be eaten.  They are now about 3cm in length and 2 are definitely platies.  The other one is a male molly who is all white so we called him snowflake.
<I see.>
He is a most unusual fish and I would like someone to tell me I am not crazy.  He behaves like a dog and appears to know his name, recognises my voice, comes to the front of the tank when he is called and will follow me up and down the tank as many times as I walk back and forth.
<Hmm'¦ do suspect you're projecting a bit here, but who knows?>
No other fish behave like this and he doesn't do this for my son or anyone else (although I am the main feeder). My family have witnessed this and find it hilarious but every one else thinks I'm nuts.  Please tell me fish can hear and distinguish sounds.
<Yes, fish can hear sounds, but not necessarily sounds outside the tank. On the other hand, fish can see outside the tank, they do learn to associate certain people with food, and many species become "tame" in the sense of swimming to the front in the expectation of food. Don't overlook the fact fish can train their owners to feed them, i.e., if they do a particularly movement, they may well learn that such a movement gets your attention and then gets you to feed them.>
<Cheers, Neale.>
Re: Molly Behaviour   1/15/12

Thanks Neale
I am basically being conditioned by a fish! 
<Could well be!>

They are smart.
Thanks again
<Most welcome.>
<Cheers, Neale>

black molly -- 10/12/11
have a black balloon molly swimming with head down why please , thanks
<Gary, I will need a lot more information than you have provided in order to help you. For starters, need to know the tank size, water parameters, tankmates, how long you have had the fish, how long has it been showing the symptoms, what are you feeding it, do you see any damage on the fish....you get the picture...to help your fish you need to help us by giving us the right information. Do get back with detailed information as stated above and in the meantime, read here -
http://www.wetwebmedia.com/fwsubwebindex/mollyfaqs.htm Good luck! Sugam,>

female molly - odd behaviour - recently gave birth; little useful data    8/8/11
Good afternoon,
we are new to the club of owning fish. Our female (Maisie) was pregnant when we bought her 2.5 weeks ago. She gave birth to approx 30-40 fry 5 days ago. Our male molly passed away 6 days ago... we returned to the store and acquired another male molly who has adapted to the tank well. The female took to him (or so it seemed) without issue when we took her out of the birthing net.
She gave birth while we were at the store... She was fine for the 1st 3-4 days...but yesterday her behavior changed. She did not eat last night - or this morning for that matter - she has been pretty much swimming in place (showing signs of lethargy), hiding behind the birthing net bobbing away, sometimes almost vertical. In addition, today she has a long clear/whitish discharge coming out instead of excrement... looks like phlegm (for lack of a better comparison). We verified the water and it is fine. Can you guide us? We suspect she is failing fast but are wondering if there is anything we can do to save her.
Julie and Laine
<Mmm, Mollies need hard, alkaline water... Some common species are brackish rather than freshwater organisms... They need quite clean water, w/ little metabolite accumulation. Please read here: http://wetwebmedia.com/FWSubWebIndex/mollies.htm
and the linked files above. Bob Fenner>
Re: female molly - odd behaviour - recently gave birth    8/8/11

thank you for your help.... I am saddened to say she did not make it through the night... :(
<Please read where you were referred. B>

Male black mollies and fry growth- 2/16/11
I was wondering if male black mollies are smaller than the females or are they the same size???
<Males are smaller by far w/ growth, age>
I was thinking of a tank of all males, like 4 in a 30 gallon. Also I have three platies fry and six black molly fry in a 20 gallon long. I notice that the platies are growing fast, but the mollies seem to be slow growing.
The store will not take them until they are bigger. How long do molly fry take to reach maturity and when can you tell the males from the females???
<Depends on conditions, feeding, foods... conditions can favour either. Do see WWM re. Bob Fenner>
Also is it a bad idea to keep a few Danios with mollies?? Danios seem so hardy. Thank You!!
<This also>

Dalmatian mollies  12/17/10
I was wondering if Dalmatian mollies grow larger than Black mollies??
At the fish store I was at the Black Mollies were listed as growing up to 2 1/2 inches and 4 inches for the Dalmatians. Since it was a big box store I doubted their information, but maybe they were right. Are Dalmatians related to Sailfins which apparently grow to 6 inches? Also are female Black Mollies more peaceful than any other molly?? Thank You!!
<It's difficult to predict precisely how big your Dalmatian Mollies will get. They're hybrids, so there's a fair bit of variation. But you can reasonably expect farmed Mollies to get to about 8 cm/3 inches in the case
of shortfin varieties, and 10 cm/4 inches or perhaps slightly more in the case of Sailfin mollies. The big Giant or Yucatan Sailfin Mollies (Poecilia velifera) are relatively scarce in the hobby, though they may be obtained through good aquarium shops and fish clubs. Do read more about Mollies and their needs here:
Cheers, Neale.>

disorientated silver Sailfin molly  6/7/10
I have a 110L tank which has been well established for about 6 months now.
I have 1 male silver Sailfin molly, 2 black Sailfin molly male and female, 2 female black molly, 4 swordtail 2 male 2 female, 1 rainbow shark and a flash Plec.
<A lot of fish for this aquarium, and not 100% compatible. For reasons stated at least twice this morning already, Mollies do best when given somewhat warmer and more saline conditions than Platies and Swordtails.
While all livebearers will tolerate a little salt, the Rainbow Shark and the Plec will be rather less happy about that.>
As I said this is a well established tank and I also have several 4 week old fry which are all doing well and finally coming out of hiding and getting on fine. I took a water sample to my local shop for testing last week, as I was adding the Plec, and they told me my ph level was 7.5 and my nitrite and nitrate levels were pretty much non existent.
<"Pretty much non-existent" isn't zero, and zero nitrite is essential.
Nitrate levels above 20 mg/l do seem to cause problems for Mollies in the long run.>
I keep my tank purely freshwater rather than brackish as I have always found in the past there was no need to add salt and have always kept mollies in my other set ups without any problems.
<You're one of the lucky ones then. Do understand Mollies don't need "brackish" conditions, but a therapeutic 2-3 grammes of marine salt mix per litre of water does lead to better success. Always has done, and no-one anywhere argues that adding salt is harmful. The difference of opinion is whether the use of salt is essential. My advice is that since it never does any harm, and something like 50% of the time makes Mollies easier to keep, it's the wisest approach.>
This weekend I have added 2 small airstones for decoration only, but when I switched them on only at a very low level, within seconds the male silver Sailfin molly got very disorientated and, although still very active, kept tipping over nose first and upside down.
<Can't see why this should be a problem, unless the air was either [a] introducing airborne toxins such as paint fumes; or [b] disturbing decaying organic matter on the sediment that then started to consume the oxygen in the water very rapidly.>
He was still able to right himself, but not for long before he tipped over again. As soon as I turned the airstones off, again within seconds, he was fine and although slightly disorientated for another hour or so, he is fine now. All the other fish in the community are fine and unaffected. Can I just add he did not at any point swim through the bubbles, but many of the others did and remained perfectly ok.
<Indeed. Fish tend to avoid air bubbles, though some don't mind them.
Assuming this is a bog-standard air pump, it's unlikely you're super-saturating the water with oxygen or nitrogen, so it isn't likely you're causing distress that way.>
Although I am not the most educated in aquariums, I have always been very successful with Sailfins and mollies over the years. I have not come across this before with any others I have kept, and as he is my favourite and in my opinion the most attractive, I am really keen to get to the bottom of this.
<No obvious reason for this at all.>
Thank you in advance for any assistance you may be able to give.
kindest regards
<All very curious. Cheers, Neale.>

Re disorientated silver Sailfin molly -- 06/09/10
Hi Neale
thank you for your very quick reply, unfortunately the above mentioned molly died over night.
<Too bad.>
I did my own test on the water and the results I got were PH 7.5 ammonia 0 Nitrite 0.1 mg/l
<This is dangerous, especially to Mollies. Zero nitrite and ammonia are essential.>
and Nitrate 10 mg/l. There was no major disturbance of any sediment and no paint fumes and it is just a small standard pump. Apart from that I have no more information to give all the other fish are perfectly happy. Once again thank you very much for your help.
kindest regards
<Cheers, Neale.>

Molly & Dollar... beh., sys.    1/18/10
I have quite a strange situation going on and I'm honestly not too sure how to go about fixing it.
<Do start by reading here:
Mollies are very misunderstood, and a depressing proportion of them end up dead prematurely.>
Recently, my boyfriend and I purchased a balloon molly as well as a silver dollar. Just the other day we also purchased a 29 gallon tank, so in a week or so we will be getting a few more of each.. the thing is, our molly seems to adore the dollar. Whether or not it's a sign of aggression, I'm honestly not sure.
<It is aggression. I've seen this same thing before with Sailfin Mollies and Australian Rainbowfish.>
Basically what is happening is that our molly is always stuck right next to our dollar. Usually that's all he does, he just sits next to the dollar, occasionally he may kind of rub up against the dollars side.. sometimes though the molly sort of nips at the dollar's side and the dollar may take off suddenly but usually slows down and the molly's right next to his side again.. now the dollar doesn't seem to mind the molly all that much- usually if the molly goes off to pick at some food or whatever, the dollar is right behind him... I've read before that sometimes mollies will nip at
other fish but not in a harmful manner. I'm not sure if this is true but I'm just beginning to wonder how much stress this is causing the dollar, if any at all... I have searched the web and cannot find this same situation happening to anybody else. As I said, in a week or so we will be moving them to a bigger aquarium, I'm just wondering what might happen if we get a few of each.. we were thinking of at least one other dollar, maybe two, but reading this site, it looks as if I'll need more...? Please tell me what you can! As I said, the molly really doesn't seem to cause any harm at all to the dollar- he seems to absolutely adore him.. and to be honest- the dollar doesn't really seem to mind the molly all that much either.. I attached two photos, both of them have each fish together.. the second one is a little tougher to find the dollar but if you look at where the molly's lips are....... I apologize for the lack of quality, I lost my camera so I had to use my phone to take the pictures.. Anyway, please let me know if this is causing stress on either fish or if it will once we purchase a few more! Thanks so much .
<Now, there are two issues here. Firstly, Silver Dollars are schooling fish. They need to be in groups of 5 or more specimens. They also get very big. VERY BIG. So unless you have a 55 gallon tank in the near future, don't keep them. These are big, nervous, herbivorous (eats plants) fish not suited to the average community tank. Now, as for the Molly. Male Mollies fight for dominance by showing off. Essentially they display their size and fins to one another, and the one with the biggest fins wins. What happens if a male Molly is in "solitary" confinement is that he looks for females (finds none) and looks for rival males (finds none). Then he looks for anything that *might* be a Molly. My guess here is that arch-backed fish -- like Australian Rainbows and Silver Dollars -- resemble the silhouette of a male Molly with erect fins. In other words, your Molly thinks the Silver Dollar is another male Molly threatening him. There's no resolution here -- the Silver Dollar can't change his shape -- the male Molly neither beats the Silver Dollar nor gets the Silver Dollar to back down. So the rivalry goes on and on. The two species are not really compatible, so I don't see any point trying to get them to live together. Mollies need very warm, very
hard, basic water, ideally slightly brackish; Silver Dollars want middling temperature, soft, acidic water. Put each in their own aquarium suited to their needs, and your problem goes away. Simple as that. Cheers, Neale.> 

Dalmatian molly swimming on side  1/12/10
I bought two Dalmatian mollies this afternoon and one of them is now acting strange. It seemed okay when I put him in the tank, but after an hour he took up a place under the filter and wouldn't move.
<Almost always, Mollies react this way when moved into poor water conditions. Do remember that Mollies are very fussy in their requirements.
At minimum they need basic (pH 7.5-8) water that is very hard (15+ degrees dH) and very warm (28-30 degrees C). Many experienced aquarists, myself included, would further insist on the addition of marine salt mix to the water as well. This raises the salinity AND the carbonate hardness. About 3 grammes per litre usually does the trick, though you can add more if you want to.>
When I fed the fish, he didn't show any interest (to be expected the first day) but the other one ate just fine. An hour ago I noticed he had moved behind a plant in the back and was tilting to the side, and after readjusting would flip to the other side. He even flipped completely over twice. I immediately pulled him out of the tank to my small extra/sick tank. He still seems to be having trouble swimming upright. When I went to catch him in the net he swam away normally. Could he have Whirling disease?
Or maybe I transported him home wrong?
<More likely he's unhappy in the tank you have him in.>
I always take a small portable tank/fish carrier, and I buy a container of Chlorine free/Oxygenated water, at about 70 degrees, to put in the tank and then slide the fish out of the bag into the tank. We have to drive over an hour to get to a fish store so I always try to transport them this way so they won't be in the bag too long. I use a small heater to adjust the temperature slowly when I get home, and then add them to my existing tank.
Maybe this stresses them out more?
<Don't think this is the issue.>
I have a 30 gallon tank with 7 Neons, one Dalmatian molly (plus the two I bought today), one small pleckolitia, and 7 small Danios/glofish mix.
<Neons and Danios both appreciate fairly cool water, around 22-25 C (72-77 F). This would be far too cold for Mollies. You cannot keep these three species together and expect them all to be healthy. Please do READ about what fish need PRIOR to purchase.>
My ammonia is at 0, my nitrites are at 0, and the nitrate is at 10. I do weekly 20% water changes and keep the temp at 72-73.
<Too cold.>
I am afraid I have brought home a diseased fish, but he appears to be perfectly healthy, no nipped fins or ich spots, except this problem.
<Problem environmental.>
The other fish was in the same tank at the store, and all the other fish in the tank were clean and healthy. Please let me know soon if it is whirling or something else. I'm not sure he will survive the night and if he dies I may take the other fish back to the store. Should I take it out and place it in my sick tank with the other fish now as a precaution? And if it is whirling or something else, can I treat it? Thanks for the help, Cristina.
<Do read here:
Cheers, Neale.>

My lovely mollies... sys., beh./comp.    8/5/09
I have a 50 gallon aquarium that holds 2 male silver dollars, 8 zebra Danios (2 of which are Glo-fish), 3 cherry barbs, 2 glass cats, and 6 mollies - one silver male, one Lyretail silver female, one black male, one
black female, one Lyretail Dalmatian female, and one creamsicle female.
<Mollies don't usually do well in freshwater tanks, and if you must keep them in freshwater conditions, you need three things: a high pH around 7.5 to 8; a high hardness upwards of 15 degrees dH; and very clean water, 0 ammonia, 0 nitrite, and less than 20 mg/l nitrate.
Virtually all Molly problems come down to people insisting on keeping their Mollies in freshwater tanks -- despite what all the books say about them often needing slightly brackish water to do well. I cannot stress this point too strongly because I get Molly questions several times a week, and they often come down to this "mistake".>
Here's the problem, the silver male is very large compared to everyone else (about 4 inches) and is causing havoc.
<Normal. Keep adding females of his species (Poecilia sphenops, Poecilia mexicana, or whatever.) until he cannot bully just the one female. Adding floating plants helps a great deal too.>
He is chasing everyone - all the females and the male, and has even nipped up the tales of all the Lyretail girls. Now, the silver female seems to be losing her color and turning slightly gray. Can I assume this is due to the stress the silver male is causing?
<In part, yes, stress weakens the immune system allowing opportunistic infections to develop. On Mollies, these usually manifest themselves as Finrot, Fungus and/or Columnaris. These three diseases are very common when Mollies are kept in freshwater tanks, and even if your Mollies were healthy enough for a while, any negative pressure on them, such as bullying, could tip the balance in favour of these diseases. So, to recap, keep more than two females per male, and keep them in brackish water so these diseases are
less likely. It's really very simple, and explained repeatedly here and in aquarium books.>
He was acting fine when we first got him, but then the silver female that was in there with him died, and he starting chasing everyone. We went and bought the new females to try to calm him down, but it doesn't seem to have worked. He especially picks on the Dalmatian - I couldn't find her for 2 days, then she showed back up with her beautiful tail looking all torn up.
Now, if she gets near him, he immediately chases her away. He doesn't bother any of the other fish in the aquarium. Is there something I can do to calm him down?
<No. Male Mollies are aggressive. Evolution has worked to cause male livebearers to be aggressive and promiscuous because they are smaller than the males and have brighter colours, so are more vulnerable to predators.
So where a female can be picky because she'll live a year or two beyond maturity, a male only has a few months, if that, after sexually maturity, so he has to drive away rival males and inseminate as many females as he possibly can. You might not like the way evolution works, but there's nothing you can do about, and in the case of Mollies, this is the reality.
You could try adding two more males of his species, together with at least four more females of his species. The males might end up directing their energies towards each other some of the time, and if you had three of them, the one dominant male couldn't bully either of the other males exclusively.
Adding one male would be a nightmare, and the dominant male would likely batter the new one.>
I feel sorry for all the others - can you please make a suggestion as to what I can do? By the way, the water parameters seem to be fine and no other fish are showing any signs of health issues (with the exception of
the graying female and the now pitiful tails of the female Lyretails).
<The graying female likely has a bacterial infection, and you will probably need to treat.>
I greatly appreciate any advice you can offer, you are the best!
<Cheers, Neale.>

Creamsicle Mollies vertical behaviours  05/23/09
Hello all,
<Howdy Glenn>
I just wanted to add a little more info to the fire. I recently acquired a foursome of mollies and shortly thereafter began noticing they would go vertical for a short period of time, and then return to normal.  The tank is a 75 running 2 magnum 350's, one through a 25 wt sterilizer, the other returning through a double BioWheel setup. The numbers are good, but they still persisted. I decided to watch very closely for a while to make sure I hadn't missed some visible symptoms, and I noticed that while they are vertical, they vibrate! If you watch closely, at least mine are shaking themselves very rapidly, in a very tight pattern. Could it be some form of digestive aid? Or perhaps trying to clear an obstruction in the gills? As I am not an expert, I will have to leave it to you guys as to any possible correlation between other species. Hope this helps sort things.
Glenn Virgin
<Interesting speculations... I don't know re root causes here... have seen mollies (et al. fishes) change spatial orientation related to flake food (over) eating at times... NealeM is out presently, but am asking for his input here as well. Bob Fenner>
TFF Squeakytoy

Creamsicle Mollies vertical behaviours 05/23/09
Hello all,
<Howdy Glenn>
I just wanted to add a little more info to the fire. I recently  acquired a foursome of mollies and shortly thereafter began noticing they would go vertical for a short period of time, and then return to normal. The tank is a 75 running 2 magnum 350's, one through a 25 wt sterilizer, the other returning through a double BioWheel setup. The numbers are good, but they still persisted. I decided to watch very closely for a while to make sure I hadn't missed some visible symptoms, and I noticed that while they are vertical, they vibrate! If you watch closely, at least mine are shaking themselves very rapidly, in a very tight pattern. Could it be some form of digestive aid? Or perhaps trying to clear an obstruction in the gills? As I am not an expert, I will have to leave it to you guys as to any possible correlation between other species. Hope this helps sort things.
Glenn Virgin
<Interesting speculations... I don't know re root causes here... have seen mollies (et al. fishes) change spatial orientation related to flake food (over) eating at times... NealeM is out presently, but am asking for his input here as well. Bob Fenner>
TFF Squeakytoy
<<Would suggest reviewing both diet and environmental conditions; does sound like "the Shimmies" to me, which is most commonly associated with water quality and water chemistry problems. Mollies rarely do well in freshwater tanks, where they're very intolerant of ammonia, nitrite and nitrate. Most aquarium books recommend keeping Mollies in slightly brackish aquaria, a suggestion I agree with wholeheartedly. As such, they're not suitable for tanks with salt-intolerant fish like tetras and barbs. Instead, keep them in a tank with hard, alkaline water (hardness 15+ degrees dH, pH 7.5-8.2) and zero ammonia and nitrite. Maintain the salinity around 6 grammes (one level teaspoon) of marine salt mix per litre, SG 1.002 at the optimal temperature for Mollies of 28 degrees Celsius. When kept thus, you should find your Mollies get better, or at the least, your healthy Mollies will stay that way. There's no actual cure for the Shimmies, but raising the temperature slightly and optimizing water chemistry and quality as described above should help. Cheers, Neale.>>

Funny Molly 5/5/09
You guys have a fantastic site! I do have one quick question. I purchased a Dalmatian Lyre Tail Molly (M) tonight. At the store he seemed to be swimming fine. In our tank he will slow his swimming and will go nose up raise his dorsal fin and kind of shake just his head. I read in other posts that they take big gulps of air but he is not near the top, he is actually near the middle. We have a 35 gallon hex tank with 2 guppies, 4
mollies (1m, 3f) and 4 platies. The water conditions are good, ph slightly high. Just wondering if this was something of concern or if he is just being "funny". Oh and the tank has been established for one and a half
Thanks a bunch,
<Can't tell at this point, but I would keep an eye on this fish... it may well have suffered some damage in the course of wherever it was bred/reared, through shipping to and through your dealer. Bob Fenner>

Mollies, beh.  -- 04/12/09
Hi, I have a Sailfin molly (male) and several Dalmatian females. i have moved them to a new, 3 foot tank, and have noticed that lately, they are a lot more active, but have taken to swimming along the surface of the water and using their tails to splash water everywhere.... they didn't do this in their old tank and i am wondering if this is a good sign or something i should be worried about, as they have already had babies, and they seem to be quite happy/active. would appreciate any info you can give me on this.
<Hello Keely, Do see here for a start:
Mollies are active fish and the males are super-aggressive towards each other and will pester females who won't mate with them. I'd recommend always keeping twice as many females as males, and to always make sure there is swimming space and hiding places for all concerned. Cheers, Neale.>

Re: Mollies -- 04/12/09
thanks for getting back to me so quickly,
<Most welcome. But please, do use capital letters next time you write; we rely on clearly written messages to make the site useful to people around the world, not all of who are text-messaging teenagers!>
i only have one male, and 5 females, and 2 of the girls seem quite happy to breed with him.
<Sounds good.>
he is not overly aggressive/bothersome to the females that don't breed.
<Ah, this is because you have lots of females. But when people buy them in "pairs", that's when the trouble begins.>
It has only been the last 2 weeks or so that they have taken up this "splashing" habit, and all 6 of them seem to do it. i know they have enough room, as i have almost doubled the tank size, and the have plenty of
room/hiding spaces which is why i am confused as to why they have taken up this habit.
<Are they jumping out of the water? Or simply being boisterous? It is normal for Mollies to "gulp" air, which they do in the wild when the water gets stagnant. In aquaria, if they do a lot of gulping, it tends to mean
water quality isn't good.>
do you feel it is something i should be concerned about?
<It isn't anything obviously bad, but I'd certainly view unusual behaviour alongside checking other parameters: Is the water hard and alkaline? Are you adding marine salt mix to the water? Is the water quality good?>
i looked at the link you provided but already knew most of the info on there.
<Glad you've done your research. Too many people buy Mollies without reviewing their need for space, water quality, and very specific water chemistry first.>
thanks, Keely
<Cheers, Neale.>

Re: Mollies -- 04/12/09
Hey, thanks again,
I have checked the water quality based on all of the info i have seen, and it seems to be perfectly within the "prime" parameters. An exact description of what they are doing is swimming normally along the surface
of the water and flicking their tails, so they are spraying water everywhere. they are not gulping or using their head in any way and it is both the males and females that do this. I have to say, i am quite glad this new tank has a lid on it, they make quite a mess.
Thanks eely
&<Doesn't sound like anything other than playful exuberance. Observe, monitor water chemistry/quality/salinity, but otherwise enjoy. Cheers, Neale.>

Mollies, beh.  01/09/09 Hi, one of my white mollies have a pin size hole on her left side of her fin not sure how she got it? She did get caught on the filter the next day is when I noticed it. <Greetings. Mollies are sometimes aggressive towards one other, and some fish (like barbs and black widow tetras) are confirmed fin-nippers that can shred the fins of their tankmates. In theory, holes in the fins tend to heal quickly. But because Mollies are delicate in freshwater tanks (or tanks with "teaspoon" amounts of salt per gallon) it is very important to observe them carefully and ideally treat for Finrot and Fungus proactively. In brackish water tanks and saltwater tanks Mollies are generally much hardier and heal without problems. Do read here: http://www.wetwebmedia.com/FWSubWebIndex/mollies.htm Lots of people make the mistake of keeping Mollies in community tanks. They're really not good community fish for a variety of reasons, and best kept in spacious, clean tanks with hard and ideally brackish water. They combine well with other brackish water fish, though purists like me would argue Mollies are wonderful fish well worth keeping in groups of their own kind only! Cheers, Neale.>

Molly Behavior/disease  1/4/09 Hello, I have a 55 gallon freshwater community tank. I have some tetras, livebearers, and small catfish. I specifically have 4 small black mollies (still babies), 4 silver mollies, and 1 starburst molly. My water is perfectly fine. My male silver molly has been acting strange. He hides in every corner he can find, and when not hiding, he is swimming behind plants, head up. He never eats the food, and just hides. He acts sick, but there is nothing on his skin. 3 of my 4 black mollies are in a quarantine tank for lip fungus. Help! <Hello Rachel. One problem with Mollies is that they are not reliable freshwater fish. Most aquarists experience what you do when they are kept in freshwater tanks: lethargy, loss of colour, odd swimming behaviour, and random diseases including Finrot and fungus. The only 100% reliable way to maintain Mollies is to treat them as brackish water fish. Buy some marine salt mix -- not "aquarium salt" or "tonic salt" -- and add the marine salt mix to each bucket of water at a dose of around 5-6 grammes per litre. Marine salt mix contains carbonate salts that raise the hardness and sodium chloride that raises salinity. Together these things stabilise the pH and reduce the toxicity of nitrate, and it appears to be these things that help. (Tonic/aquarium salt only contains sodium chloride, and so doesn't do both these things, and is consequently a waste of money.) Mollies thrive in brackish water, and at low salinities so will other livebearers including Guppies, Platies and Swordtails. But do understand that most catfish and tetras do not appreciate brackish conditions, and consequently shouldn't be kept with Mollies. It's a very common mistake for people to buy Mollies for community tanks -- despite the fact most aquarium books state clearly Mollies prefer slightly saline conditions. Do read here for more: http://www.wetwebmedia.com/FWSubWebIndex/mollies.htm Cheers, Neale.>   Thanks! <Most welcome. Neale.>

Balloon Mollies - One of 'em not mixing (Behaviour; environment?)   10/17/08 Hi, <Hello,> We've recently bought three balloon mollies (One male, two female). The male and one of the females are instantly pals, always shadowing each other and playing. <No, they're not playing. The male is trying to mate, and more than likely the female is trying not to! It's always dangerous to anthropomorphise when talking about animal behaviour. Most animals I know get very offended when I assume they think like humans!> They were quick to begin exploring the tank after being introduced. The other female however, does not join them. She seems to spend a lot of time against one side of the tank. She's not up at the surface, nor hiding from sight. She just keeps going up and down as if she's searching for a way out. They are the first 3 fish in a 30 gallon tank. The water properties are good (7.5ph, 0.25ppm nitrate current, 81 degrees F) <Hmm... do you really mean "0.25 ppm nitrate"? That's very low, and not many consumer-grade test kits register such tiny amounts. If that's 0.25 ppm nitrite (note the "I" in there, as opposed to the "a" in nitrate) then we have a whole different ball game. Mollies are incredibly sensitive to nitrite, particularly if (unwisely) you have opted to keep them in freshwater conditions (which, frankly, hardly ever works out well). If you have a nitrite level that is detectable, then you have too much, and Mollies respond by getting sick, and then dying. Consider them "miner's canaries" if you like. If this is a new aquarium, I'd heartily recommend switching to slightly brackish conditions by adding marine salt mix (Instant Ocean, Reef Crystals, etc.) at a dose of, say, 4-6 grammes per litre. Sodium chloride has a useful property of undoing some of the damage caused by ammonia and nitrite, and marine salt mix also contains other minerals that buffer the pH and hardness. Net result, Mollies thrive instead of survive. This low dose won't harm your filter. Since Balloon Mollies shouldn't be mixed with any other type of fish, the fact you're adding salt isn't an issue in terms of tankmates. Problem solved.> Now, she is white and the other two are black, can that be an issue? (the two black ones seem to gently 'recruit' her away from the side of the tank from time to time) <Nope; all the same species, or likely hybrid.> Also, she is significantly more plump then the other two. If she's pregnant, will she be anti-social? <Nope.> Thank you in advance, Nick <Cheers, Neale.>

Re: Balloon Mollies - One of 'em not mixing (Behaviour; environment?)   10/19/08 Hi Thanks for the prompt reply. <Most welcome.> First off, I did mean 0.25ppm Nitr[I]te. I'll admit, we only allowed the new tank about a week and a half of cycling before getting the mollies. We figured three of them in a 30 gallon would help speed the cycling process (with daily partial water changes until it settled). <Then that's why your Mollies aren't well. Case closed. Mollies just don't tolerate nitrite or ammonia well, at least not in freshwater conditions.> As far as the salt goes, we have very slightly brackish water (about half the recommended treatment - so a tablespoon per 10 gallons) as we did intend for this to be a community tank. <This isn't "slightly brackish" anything. Slightly brackish is around SG 1.003-1.005, 6-9 grammes per litre. Six grammes of salt is about one level teaspoon, and one US gallon is 3.75 litres. So if my math is correct, SG 1.003 is about 22.5 grammes of marine salt mix per US gallon, or just under four teaspoons of marine salt mix per US gallon. Ten US gallons would therefore need 4 x 10 teaspoons = 40 teaspoons, and 40/3 = 13.3 tablespoons of marine salt mix. Your dose of salt is quite obviously not nearly enough to make a difference. I just can't stress strongly enough how important it is for Mollies to be kept -- long term -- in brackish water.> (plans were for two angels, three mollies and 5 or 6 medium tetras/Danios/somethin'rathers) <Forget it. Mollies don't work with these fish. Instead look for other brackish water (or at least salt tolerant) tankmates. Very many options, including Guppies, Halfbeaks, Limia, gobies, sleepers, certain cichlids, even certain catfish. Plenty on brackish water species at WWM.> However!... The white molly I wrote to you about gave birth and now she is social with the other two. Shortly thereafter, the black female went into hiding on the gravel, under a log and later that day, she started birthing too. I'm sure a number of 'em got eaten but we have spotted and netted 18 fry in all. We don't have a separate tank for 'em so I'm keeping them in the breeder trap for now. <Cool.> I guess I'll add the bit more salt and just look forward to watching some of these little ones grow up instead of getting other fish. lol Will they be okay in the breeder trap until they are large enough to swim free with the adults? <The babies will be fine with their parents once about 1.5 cm long, which should only take 6 weeks or so.> Nick <Cheers, Neale.>

Re: Balloon Mollies - One of 'em not mixing (Behaviour; environment?)  12/5/08 Hello again, how's it going? Good, I hope :-) So to update you, our tank finished it's cycle with the mollies in it, water tests are perfect now and we have not lost a single one of the fry we had caught. We've added much more salt to keep 'em happy and added three guppies to the mix... <Sounds good!> Now we're seeing a problem: After about a week and a half of being introduced, one of the female guppies started picking at the side of our white molly. She managed to pluck off some scales, and a part of her side fin before we separated her (the guppy) from the rest. We don't have another tank so we kept her in the breeder for three days. We have raised the temperature (to 83 degrees) and added some extra "stress coat" product to promote fast healing. Upon her release though, the guppy goes straight for the white molly again! (Guppy pays no attention to the other two Black Mollies, who sort of come to defend the white one, but are too passive to really make a difference). The white molly does nothing to defend herself but hide. Now, even the mollify-fry have started picking at her... Why do you suppose they're all after her? There is no way for her to recover in the tank unless we isolate her in the breeder but what do we do if everyone in the tank keeps picking at her when she's all better? Thanks again, Nick <Guppies (and even more so Mollies as well) are adapted to graze, and have mouthparts that open up in such a way they can scrape flat objects. In the wild, that means they can rasp algae away from rocks and plants. Now, the problem is that if they find something else tasty, they'll rasp away at that. Algae wafers on the bottom of the tank, a dead fish, or indeed a patch of mucous or blood on the side of a slow-moving tankmate. In this instance, isolating her in another tank or even the breeding net will be the only way to stop this. I don't often recommend putting mollies in breeding traps, but right here, right now, this might be the only way forward. Cheers, Neale.>

Marble Molly behavior 7/6/08 Hi... I have a question about a different behavior we have noticed recently with one of our Marble Mollies. We have 2 males and one female currently in our aquarium and all interact with each other wonderfully and seem to be doing great. Within the last day or two however, one of the males has been swimming around with his top fin standing straight up - looking like he has a Mohawk. What does this behavior mean and is it something we should be concerned about? Jaime <Hi Jaime. Male Mollies display to one another and to potential mates. By raising their dorsal fins, they make themselves look bigger and more impressive. So that's normal enough, and simply means the males are sexually mature. Now, here's my concern: two males to one female is a terrible ratio. The males will constantly be harassing the poor girl. They will be chasing her, trying to insert their gonopodia so that they can fertilise her. It's essentially perpetual gang rape, day-in, day-out! Needless to say this is stressful, and the females commonly end up aborting their fry instead of carrying them to term. In the wild females live in big groups, and that allows them space from the males, who actually fight amongst themselves to get sole access to a group of females. But in the aquarium the only kind way to keep Mollies is to keep at least two females per male. That will balance things out in the favour of the females. Obviously Mollies also need lots of space, certainly nothing less than 75 litres/20 gallons so that the fish can spread out and, if necessary, hide away from each other if they need some rest. This benefits the males, which tend to fight, and the females, which are constantly having to deal with males trying to inseminate them. Hope this helps, Neale.>

Molly question, behavior 7/1/08 I have a female Lyretail mostly black, (not enough white to be Marble or Dalmatian), molly, that is constantly being pestered by a male Lyretail creamsicle molly. I've seen them mate at least 100 times. Will he ever stop pestering her? <Not likely.> Assuming she is with fry, when should I expect her to give birth? <About every 6 weeks or so depending on conditions.> Is there any way to tell when she is ready? <Easiest way it that she will be especially round, also sometimes a gravid spot can be seen. See here for more http://www.wetwebmedia.com/fwsubwebindex/livebrrreprofaqs.htm .> What color do you think they will be? <Impossible to tell, could be almost anything.> I heard that black mollies only give birth to black female mollies no matter what color the mate is, but I find this questionable? <This is not my experience.> Thanks, Laura <Welcome> <Chris>

Aggressive Molly 2/23/08 Hi, I am fairly new to the hobby...I have in my tank one black male molly, one male Sailfin molly and four male guppy's in brackish water. The guppy's are new additions and the black molly seems to chase all of the guppy's constantly to the point were they just hide amongst plants. This is not new behavior it did the same with the other black molly I used to keep, to the point I am convinced it died from the stress/bullying...just my guess it may of been sick/weak but im sure it was bullying. I don't want the same thing to happen to My Guppy's is the only option to remove the problem fish? I don't have another tank so I would have to take it back to store. Would you recommend taking the black Molly out of the tank? <This behaviour is (unfortunately) all too common in home aquaria. There really isn't a fix. Male livebearers don't live long (their smaller size and brighter colours mean males are more vulnerable to predation than the females). So all they think about is monopolising access to the females as much as possible until they die! Mollies and Guppies both belong to the same genus, Poecilia, and view one another as potential rivals. Since the Guppy is so much smaller than the Molly, it is typically the Guppy that gets bullied and the Molly that does the bullying. It is universally good advice to keep livebearers as one species per tank and ideally one male per 3 or more females to avoid precisely these sorts of problem. Anything else is ALWAYS a gamble; either the males fight with each other the males harass the females, leading to miscarriages (and obviously fewer babies). Adding additional females may dilute the problem somewhat, but it never really fixes it. Cheers, Neale.> 

My Mollies are all fine thank goodness.  -01/30/08 <Good.> This morning when I woke up I sat to watch my fish. <Ah yes! Best start to the day...> I noticed that one of my males was injecting his anal fin into one of my females. He is also sniffing her under belly. From my research I learned that means the female is pregnant. <That's the theory, anyway. The anal fin is effectively a penis, and used to direct a packet of sperm into the female where the eggs will be fertilised.> I also noticed that he was also sniffing the other females' under belly. <I'm not sure 'sniffing' is the word here, more likely just looking to check she's a she and not a he.> Did he make those females pregnant too? <Almost certainly.> One thing I think is out of the ordinary is even though he isn't near a female or injecting a female he keeps moving his anal fine back and forth. <Completely normal.> What is he doing? <Enjoying himself.> Great website, Karleigh <Cheers, Neale.>

Mollies being panicked to see people... 12/30/07 Dear Neale, <Kathy,> I have two molly tanks (both are about 38 gallon). In one of them are 9 bigger mollies. They used to be very happy to see me come near their tank knowing that I am going to feed them. But recently they become very scared of people (almost panicked to see any movement I make). I am not quite sure what caused such big change in their behaviour. <Hmm... water quality/chemistry changes can make fish nervous, and such behaviour is one of the best early warning signs of such troubles. In addition, check for things like sources of noise as well as the loss of hiding places, e.g., if you've cut back the plants or moved the rocks about.> I have to move slowly when walking towards the tank. They all hide in one corner... Until they see some food floating do they slowly come out to eat. After the meal, they again hide themselves if I am still around. <Odd. I have to ask: are they in freshwater or brackish? Mollies are sensitive to low pH, low hardness, and high nitrate, and adding marine salt mix, even at fairly low doses, will help here. Common aquarium salt will detoxify nitrate, but obviously doesn't do anything to raise the hardness or pH.> The orange molly in that tank is sort of aggressive. She always chases away every fish. But she has been in that tank lone time. This change just started a week ago. Do you have any suggestion as to what I can do to find out the cause or correct the situation? <Mollies do tend to be aggressive; this is a real problem with these fish, and one not a lot of people are aware of. In any case, there really aren't any "fixes" beyond [a] adding more females to dilute aggression and [b] providing more hiding places to break up the line of sight. Floating plants are especially good, but things like clay flower pots and tall plastic plants are great too.> Thanks for your time and wish you & your family a happy & prosperous new year of 2008! <And likewise to your own kith and kin!> Kathy <Cheers, Neale.>

Mollie and Platy beh.   12/28/07 Hello, First, tank detail: The livebearers: 1 Dalmatian balloon molly <... Have you read on WWM re?> 1 Red Wag (?) platy The grumpy: 1 Bumblebee Goby <Mmm, this is a brackish water animal> The amphibious: 1 African Dwarf Frog The clean up crew: 2 Ghost shrimp 1 Kuhli loach 1 Otocinclus They live in a 5 gallon (18.9 litre) tank (let it be known now that I am aware the tank is small, but I am diligent with the water chemistry), with extremely closely watched parameters, and large water changes at least once a week. <Good... hopefully not too much change with the water...> Tank temperature is generally in the mid-high 70s, <You have a purposeful heater?> with incandescent light to promote algae growth for the oto. Nitrates slightly high, <How high is high?> all else is normal, absolutely no ammonia in the water. Medium blue substrate, small terra cotta pots for hiding spaces, as well as clear marble aquarium decor. Includes three types of live plants, the one in question being the pongol sword, which looks exactly like this: http://www.aquaplantas.com/images/fotos_plantas/0158-Clorophytum-P-Sword.jpg <Mmm... am compelled to state that this, aka Spider or Ribbon plant is NOT aquatic... See the Net re> Here, finally, comes the question: I first noticed this behavior with my molly: it seems to be scratching itself against the sword, the broad portion of it. However, it does this with ONLY the sword. It does not scratch against the gravel, filter, or the other plants or aquarium walls. Just now, I noticed the platy doing the exact same thing. Again, only with the sword, nothing else in the tank. What is going on here? <Some scratching is natural... not indicative of disease...> Do they just like the way it feels? Neither of the fish appear to be infected with anything, all of the creatures are eating healthy, and they are all active. I have one more question, this one should be easier: my platy has the tell-tale dark spot of the preggers female. But it also has the gonopodium. Did I receive a hermaphrodite? <Not likely... but it may be changing, or expressing itself as one or the other...> Thanks in advance, Alex. <Do see Neale's pc. re Mollies: http://wetwebmedia.com/FWSubWebIndex/mollies.htm And elsewhere on WWM re Brachygobius, and start dreaming and scheming (if you haven't already) for another or larger system... you need it. Bob Fenner>

Re: Mollie and Platy beh.... Kings and Queens of De Nile  12/29/07 Thanks for your reply, I have, in fact, been looking out for a better system, but for now, I think this could do. <Mmm, not with the mix of species you have> The molly appears to be quite happy, and because every time I change the water, I also rearrange all of the plants and decorations (much to the dismay of the loach) so the molly may not get bored for a while. I don't actually have a heater, but the bulb seems to be doing well enough on its own. If the temperature ever steadily drops beyond what the fish can handle, I will buy a heater. <Uhh... you need one now> And about the platy hermaphrodite... <Serial...> yep, she had babies. Had to fish out around twelve of the little buggers. I'm keeping them in a half-gallon tank (it's all I have now) and feeding them ground shrimp pellets. I haven't had a chance to get more suitable food, but I may be able to wing it with hard-boiled egg yolk and minced bits of worms. I'm currently lighting their tank with an old-style desk lamp... you know, the ones that get extremely hot to the touch. I'm positive the goby type that I have in the bigger tank is the one that can live in freshwater. <Please send along an image> About the sword.. I had suspected as much, but the molly and platy seem to enjoy it so much, I may just keep it. Regards, Alex. <I'd keep reading. BobF>

Re: Mollie and Platy beh.... More chatting, now re Tetras  12/29/07 Thanks for the continuing suggestions, you'll be pleased to know, I gave up the molly and goby in favor of tetras. Much easier to deal with. <Hmm... oddly enough, doesn't always work out this way. Cardinal and some other tetras can sometimes be disappointingly short lived in very hard (20+ dH) water, whereas gobies and Mollies in hard water with a little salt added are very, very durable. But still, if you don't want to keep a brackish system, then there's no mileage in trying to keep brackish fish in plain freshwater.> I'll look in to a heater... what's the optimal temperature for this tank to be at? <Unless otherwise stated, tropical fish should be kept at 25C/77F. A degree or two either way won't make much difference, but most tropicals will weaken and die below 20C/68F. Conversely, keeping fish above 28C/82F can cause problems with oxygen starvation and short life spans.> Can you suggest a good temperature to keep the baby fish? It's around 80F in the tank, I brought it down a little because I'm afraid of frying the fry. <Nope, keep the fry at the same temperature as the adults.> Regards, Alex <Cheers, Neale.>

Re: Mollie and Platy beh.  12/29/07 Thank you very much for your help and suggestions, guys. I am hopefully well on my way to having a happy tank. <Very good.> I have rummy-nose tetras.. so far, they seem to pretty much stick to themselves. <These are excellent fish. There are at least two different species sold as these, but in either case provided they are given soft, acidic water conditions they are quite hardy and long-lived. Tend not to do well in hard, alkaline water though. Do keep in groups of at least six, or they pine away.> About the heater: I hate to sound to skeptical, but are you sure it is required? <It's really as simple as this: if the climate in your house is identical to that of the Brazilian rainforest, then no, you don't need the heater. But if your house gets colder than the Brazilian rainforest, then you need a heater. In other words, a daytime variation between a peak at ~25C/77F in the day and a low of ~20C/68F at night will be fine. When kept at the wrong temperatures, fish either die from suffocation/heat exhaustion (if too hot) or immune/digestive system failures (if too cold). Your move.> I keep the light on in the tank at least 10 hours of the day in order to promote algae growth, and the temperature through that alone hovers around 78F (I have one of those 'ballpark' strip thermometers). <Doesn't matter what sort of thermometer you use, so long as its accurate to within a degree or two. Given a basic, LCD stick-on-the-tank one costs very little (they come as free gifts on all kinds of fish kit) there's NO excuse for not using one.> I NEVER let the water drop or rise out of the 70s. The fry tank is now at the same temperature. <If this is so, then fine.> I can't remember where I read it, but during my reading up on how to care for livebearers, it was mentioned that the fry enjoy high-protein diets. <Garbage. Livebearers (with a few exceptions like the Pike livebearer) feed almost entirely on algae and mosquito larvae. Both of these are low protein foods, algae more so than mosquito larvae, but mosquito larvae are still only something like 4% protein. The vast majority of dietary problems with livebearers come from lack of fibre -- greens -- rather than lack of protein. All this will be explained in any book on livebearing fish, of which there are many.> Somewhere it was also mentioned that hard-boiled egg yolk works. I mashed a small portion of an egg yolk to a pulp in a small dish of water and fed it to the fry, and they ate with gusto. <This is an old-school treat for fish fry, and does indeed work well. But it's a treat, maybe once or twice a week. For the rest of the time, algae, Algae, ALGAE! There are plenty of algae-based (often Spirulina) flake and dried foods in the shops, or else you can use algae-covered rocks from green ponds or chop up Sushi Nori bought cheaply from an Asian food market.> Should I continue this diet? <As a treat, sure, but it isn't required.> Should any greens be involved? <Yes! Livebearers are omnivores, just like us. And just like humans: without meaty foods, they're fine; but without green foods, they get sick and die!> Thanks for all the help! -Alex. <Cheers, Neale.>

Re: Mollie and Platy beh.   12/31/07 Thanks very much for the heads up about the fry! I'll start adding greens immediately. And thanks very much for all the other information! If I have anymore questions, I will be sure to contact you. Regards, Alex. <Glad we could help. Cheers, Neale.>

FW, ammonia, Molly size Qs   11/28/2007 Hi- <Howdy> I am a beginning aquarist. I bought 1 platy and 2 mollies (Silver and Dalmatian) to start my 10gallon tank. I didn't have an ammonia test at the time (stupid I realize now) and the mollies quickly developed ich and died. The platy is still alive. I decided that I would just keep the platy for now, wait a month, or until the cycle begins and then gradually add more fish. My sister in effort to be nice to me bought me 1 HYPERLINK " http://www.liveaquaria.com/product/prod_Display.cfm?pCatId=1055" Black Lyretail Molly, 1 Creamcicle Lyretail Molly, 2 Zebra Danios and a sail as a surprise for me. I wasn't ready for that many fish- but now I have them. I have read many times that zebra danios are to be kept in groups of 5 or more. Should I buy more Zebras? Would that be overcrowding my tank? <I would hold off on adding more Danios... As you state... it's getting crowded, and your livebearers may well have babies> Also, how big do the Creamcicle and Black Lyretail Mollies get? <In such a small tank... likely about two inches in length. In larger systems, about twice this> I have been reading a lot of websites and it seems that everyone has a different answer (especially with the Creamcicle one). <You can look up the names under the word: Mollienesia... the genus... and see that various species, likely sphenops in this case, do grow to larger sizes in bigger settings> I have decided to do frequent water changes to counteract the huge ammonia spike. Is this the right thing to do? <Is one way to go... Please read here: http://wetwebmedia.com/FWSubWebIndex/fwn2cycfaqs.htm and the linked files above.> Help! Sincerely, Bea <Bob Fenner>

Molly Flashing  11/28/2007 Hi. I have a 10 gallon aquarium that I use for Molly fry. I've noticed that the fry like to bounce off the rocks in the tank. They're not rubbing their bodies, just a quick rub of the head area. Most of the fish in the tank do this at some point. They all appear healthy, are growing and feeding vigorously. We have only lost two babies out of approximately 50 that have passed through the tank since July. Is this behavior normal or a sign of a parasite? Thanks, Joyce <Hello Joyce. Are you adding marine salt mix to the aquarium? And what's the water chemistry? Mollies (and indeed most other fish) scratch their bodies when they are irritated. Sometimes this can be a sign of illness, specifically parasites that attack the skin and/or gills. But it can also be an indication of water chemistry issues, particularly excessively low or high pH levels. Just to recap, Mollies need very hard (ideally over 20 degrees dH) water and a pH of not less than 7.5 and ideally around 8.0. While not all Molly keepers agree, there's a widely held view that adding marine salt mix to the aquarium is beneficial. Wild Mollies are common in brackish water habitats, and when kept without salt in the water it is common (if not universal) that Mollies become more sensitive to infections such as Finrot and fungus. Salt also reduces the toxicity of nitrate, which Mollies appear to be extremely sensitive to. Marine salt mix (as opposed to generic aquarium or tonic salt) contains carbonate salts that raise the hardness and prevent acidic conditions in the aquarium, and this also has a dramatically beneficial effect on Molly health. From my experience, the vast majority of instances where people have Molly problems, those people are keeping them in tanks without marine salt mix. I'd recommend adding 3-6 grammes of marine salt mix per litre of water, and then seeing how your fish do. Cheers, Neale.>

Re: Molly Flashing 11/28/07 Hi Neale. Thanks for replying. I guess I should have listed the water conditions in my first email. All levels are good, (PH around 7.9), our water is naturally very hard and alkaline. <Excellent.> We do 20% water changes once a week. <Ramp that up to at least 30% per week and ideally 50%. Mollies do not like nitrate, and it seems to be one triggering factor being ill-health.> I've heard that Mollies prefer saltier water, but we have two small Corys in with them, so don't want the Corys irritated. <Fundamentally Mollies and Corydoras can't be mixed. End of story. It's a shame people sell Mollies as "community fish" because they're not.> What has me curious is that none of the fish seem stressed or sick. They don't rub, just bounce off their heads. The two five month old males that are in the tank are gorgeous and lively, but they too flash off the rocks once in a while. I'm thinking if it was a parasite or illness, these fish should show some sign of it by now. <I agree, but what you're describing simply isn't normal. Hence the need to try and narrow down the possible causes. Parasites on the gills (typically Ick or Velvet) plus improper/fluctuating pH are the classic causes of "flashing" behaviour.> So the water conditions sound more likely, even though the numbers are good. <Do check the ammonia and nitrate levels, if you can. While nitrite is the thing people usually check first, with good reason, nitrate especially is something that you have to watch with Mollies.> Hmm, will have to investigate that possibility more carefully. Thanks for your help. Joyce <Good luck, Neale.>

Att Neale: An observation about Mollies, beh.  10/16/07 Hi Neale! <Hello Audrey,> I read your answer to the person who had questions about Mollies. This person had a concern that one of his Mollies tilts slowly until it's facing up. You expressed a concern that there might be a water quality issue. <Not so much a concern as a statement that Sailfin mollies can supplement ordinary breathing by gulping an air/water mixture at the surface. See here at the Florida Museum of Natural History: http://www.flmnh.ufl.edu/fish/Gallery/Descript/SailfinMolly/SailfinMolly.html. , under "Habitat".> I don't doubt your knowledge (so much more extensive than mine!) but I have an observation to contribute. <Very good...> I've seen the tilting upwards in a lot of new Mollies. Mine didn't do it anywhere close to the surface, so I doubt they were trying to breathe, and they were in an established tank. Most of my Mollies stopped doing this after a few weeks. One never stopped. Some never displayed the behaviour. They just suddenly stop swimming, slowly tilt upwards until they're completely nose up, then just as suddenly start swimming normally again. It used to totally freak me out. <Interesting.> Mollies are constantly skimming the surface, but when they do it they're horizontal. I've never seen one doing it nose up (except when fighting for a piece of food, of course). If they were trying to breathe, I'd expect them to position themselves horizontally just under the surface and skim (their mouth is kind of pointing up already, so that's a natural position). <Hmm... not sure. To use the surface layer of water, the Molly needs to tilt slightly upwards, simply because the mouth is somewhat lower than the top of the head. It's the top 1 mm of water they need, because that's where the oxygen exchange occurs. When they're feeding, Mollies adopt a variety of orientations. They have skulls and jaws modified for grazing algae, and when doing this orient themselves so the jaws can scrape flat surfaces. They also eat insect larvae, and this is where the upwards tilt of the mouth is useful, for getting mosquito larvae at the surface.> I'll tell you about my troubles with illnesses in another email. I think I might *finally* have a clue about what's happening to my Mollies. And I have pretty gross pics to show you (they will make a nice addition to the illness pages). <Ooh, what fun!> Enough babbling for now. Have a nice day! <Thanks, and you too.> Audrey <Cheers, Neale>

Molly Behavior  8/5/07 Hello again! It was a long time I didn't ask a question. Can you please help me in my problem about my mollies. I have 2 golden dust molly and they are both female the problem is one of them attack the other one, also in my 2 balloon female molly. The stronger one (I guess) is attacking the weaker. Is this only mean I need a male for them? Also I saw small black spots in their body, and seems they are scratching in the gravel. Is this a disease, how can I prevent it? Please reply soon, I'm so worried about them. Thanks <Greetings. Mollies are notorious for bullying one another, especially when kept in too-small an aquarium. There's not much you can do about it except increase the size of the group. This assumes you have the space in your aquarium for them. It's usually the males that are bullies, so what you are reporting is unusual. Adding a couple more females would be the best thing. Adding a male wouldn't help at all! Black spots are typically associated with infections of external lice, flukes, and worms. The standard way to treat this would be using an anti-fluke medication from your retailer. However, since you're keeping mollies, an alternative approach worth considering is moving them to a brackish water aquarium at 25-50% seawater salinity (SG 1.005-1.010). You could also raise the salinity in the existing aquarium over a few weeks to allow the filter to adapt. The salty water should shift any external parasites quite effectively, especially at the higher end of the salinity range. Maintaining mollies in brackish water will benefit them in many other ways besides, and is in my opinion by far the most intelligent way to keep these fish. Cheers, Neale>

Balloon Belly Molly Question, beh.   7/26/07 Hello. I am rather concerned about a balloon belly molly I purchased today. She seems to be having some kind of equilibrium problem. She swims frequently, but rather awkwardly and seems to have to try a bit too hard to stay lower in the tank. It almost seems like she is over inflated at times but then she'll do an odd nose dive and I get even more confused. She has been eating and defecating normally and shows no outer signs of parasites. I cannot tell if she is pregnant because of her coloring. Could be some kind of parasite issue or a swim bladder problem? Or if it is just a quirk or something explained by pregnancy that I shouldn't worry about? I isolated her several hours after introducing her to the tank, if that helps. Thanks! <Ave! Unfortunately, what you describe is rather common among balloon mollies as well as "balloon" shaped goldfish, and for the same reasons -- inbreeding to produce these deformed body shapes has messed up what evolution achieved in terms of swimming ability. It doesn't take much to totally throw them off balance, and things like constipation, which moves the centre of gravity, cause swimming ability to diminish greatly. So, let's review: Mollies are herbivores in the wild and in the aquarium. They need greens (i.e., fibre) much more than they need standard fish food. (Standard fish food is about as healthy for them as feeding t-bone steaks to a sheep would be.) Double-check you're using an algae-based livebearer flake food, for example one based on Spirulina. Also check your offering fresh greens like sliced cucumber, blanched lettuce, spinach, squashed tinned peas, and so on. Actual algae from a pond or as Sushi Nori is also very helpful. Meaty foods (like brine shrimp) or regular flake food should be used maybe 1 or 2 times per week. Secondly, mollies really do best in brackish water. The actual salinity doesn't matter all that much, but the combination of higher pH, higher hardness, and raised salinity seems to help them by every relevant marker. A box of marine salt mix like Instant Ocean is what you want (not tonic salt or aquarium salt) and the dosage needs to be around 3.5 grammes per litre upwards (that's about 10% seawater). Other livebearers will thrive in such conditions, as will a variety of salt-tolerant species like glassfish, rainbowfish, and halfbeaks, so finding tankmates for mollies isn't in the least difficult. Thirdly, mollies are sensitive to a neurological disorder called "The Shimmies". Poor water quality seems to be the trigger here. While there's no guaranteed cure, switching from fresh to brackish water conditions seems to help in most cases. All else being equal, these tips will guarantee your mollies are in peak health and should help your unbalanced molly recover. Cheers, Neale.>

Damnation Molly Mom and Her 4 Mo. Old Babies behavior   7/7/07 Hello! In March I wrote to you about my new molly fry and I must say you were extremely helpful. Thank you Tom for all of your insight! <<Hello again, Bridgette. Glad I was able to help!>> I currently have 1 female molly, her 11 4 mo. old babies, and 3 new fry in a 10 gal tank. The female ran the male to his death after she gave birth to the first 11 fry she had. <<I recall this from our last conversation, Bridgette, though it's often the other way around. You mentioned she was aggressive, though.>> I am going to buy a 29 gal tank this weekend. Will I need to run this new tank for a month or so before I separate them? <<The new tank will definitely have to cycle, of course. There are ways to speed up the process, the fastest being the use/addition of BIO-Spira (a Marineland product) which will accomplish this virtually instantly. Not exactly inexpensive but the benefits are pretty obvious.>> I was thinking of putting females in one and males in another. <<A good way of heading off a population explosion! :) >> I know this little tank is overcrowded and need to do something about it right away! <<Agreed.>> Also, I've noticed for the last few days that the male 4 mo olds have been looking like they are almost trying to attach to their mother's anal fin. Are they trying to mate with her? <<A pretty good bet that there's interest in this regard.>> Thanks again, as so many people here say, this site is wonderful! <<Very nice to hear from you again, Bridgette, and thanks again for the complimentary words. Keep up the good work and continued good luck. Tom>>

My golden molly is turning black...  6/12/07 Dear crew: <Hello.> I first off want to apologize for my lack of knowledge of fish completely. <Hmm... not a good start. When caring for any animal, it is always wise to read first, then buy the animal, not the other way around.> That taken care of, I bought a gold molly to keep my albino... side sucker fish company so he'd have a friend. <What's a "side sucker fish"? I'm guessing either a Plec (an armour-plated catfish) or a sucking loach Gyrinocheilus aymonieri (a minnow-like fish with a sucker mouth). Either way, appallingly bad choices for neophyte fishkeepers. Plecs grow to around 30-60 cm depending on the species very rapidly and eventually need massive tanks. Sucking loaches also get big (around 25-30 cm) but top that off by being among the nastiest-tempered fish out there. Either way, you will need a tank containing at 200 litres within even the medium term (6-12 months). If you don't have that, return them. One other thing: mollies are extremely delicate when kept in freshwater tanks, and the only sure-fire way to keep them healthy is to keep them in brackish water. Brackish water is unacceptable to both the catfish and the sucking loach. Now, if you feel the need to keep mollies in freshwater despite the fact some or all of them will get sick, you need to ensure the following: Nitrates less than 20 mg/l; pH 7.5-8.2; hardness 20 degrees GH or more. Skipping on any of these is the express route to mollies getting fungus, finrot, and the "shimmies" (a type of nerve damage disease). Don't believe me? Stop by any fish forum you like and review the questions in the Livebearers section. The number of messages about sick mollies will stagger you. I feel I say this every week, but mollies just aren't good fish for beginners and they categorically aren't community fish by the generally accepted meaning of the word. Have a read here: http://www.wetwebmedia.com/FWSubWebIndex/mollies.htm and some of the FAQs as well.> I've had these fish for about 3 months and all of a sudden my gold molly is turning black, starting with the tail. <Almost certainly just genetics. Assuming the fish is otherwise healthy and the skin isn't rotting or something. Mass-produced mollies are not "quality controlled" so you have no guarantee they are "pure bred" in any way. So, it's basically a case of enjoy your newly metamorphosed fish!> I've tried doing some research and I can't figure out if this is just a gold molly turning into a Dalmatian molly (do they do this?) <With quality stock, no.> or if it has some sort of problem... in which case I'd like to help. <No, nothing you can do.> Thanks! Jen <Good luck. Mollies are among my favourite aquarium fish, but they are demanding and they do need special care. It's a shame they're so widely sold, because people assume they're easy fish. But kept well, few fish combine personality, colour, and easy breeding so well. Worth sticking with, and learning about. Cheers, Neale>

Mollies' eating my plastic plants -- 06/11/07 Hi, <Hello.> A couple of questions for you? <OK?> I live in the UK in Devon. I have just started keeping fish, well 12 days ago. I got my first fish a black Mollie and a silver Mollie three days ago. They are doing ok. I have a 35 litre tank, with plastic plants. <Your tank is probably a bit small for mollies. Bear in mind some species can get to 15 cm in length, if not more, and most of the common varieties in the trade will certainly be in the 5-8 cm bracket when fully grown.> I have noticed bite marks in the plants. Are they just testing or should I get them some real plants. <I couldn't imagine mollies actually damaged plastic plants, so that's a first to me. Anyway, they are doing their level best to demonstrate their need for green foods. Use vegetarian "livebearer" flake (NOT generically tropical fish flake except as a treat) plus green foods like Sushi Nori, blanched lettuce, algae wafers, sliced cucumber, tinned peas, etc. Mollies are herbivores in the wild, so try and match that in captivity.> If I do what plants would you recommend considering I plan to add a small salt content. <Almost all hard water tolerant plants thrive at the low specific gravity (SG 1.002-1.003) mollies relish. Java fern, Java moss, and Anubias are perhaps the best plants because they come attached to bogwood so are easy to "install" without fussing over substrate. They are also ignored by most herbivorous fishes. Failing these, Vallisneria, Hygrophila, Elodea, Ceratophyllum, Cryptocoryne wendtii all work well in low-end brackish tanks.> (Not changing over fully just adding the 1tsp per 5ltrs that everyone recommends. <Don't trust anyone who recommends "spoons per litre" amounts, because it's a meaningless measurement. Once the box of salt is opened, it absorbs water, so over time, each teaspoon contains less and less salt. Ideally, use a hydrometer to measure the specific gravity. A basic floating glass hydrometer will cost about £5. You want about SG 1.002-1.003, or 5-6 grammes of salt per litre. Make up the brackish water as per the instructions on the box, and then measure the specific gravity (SG). Add more water or salt as required.> Also I have read many articles especially on your site regarding adding a little salt. I plan to do this on the next water change. I have added the salt to the new water and plan to add the water slowly as I refill the tank from the water change. Is this a good idea? <Adding salt to the water before adding it to the aquarium is exactly correct. Don't forget that any time you top up the tank due to losses from evaporation, *that* water should be freshwater without salt. The salty water is only for water changes.> Thanks Doug <Cheers, Neale>

Black molly question... beh./sys.  4/10/07 Hello WWM, <Didi> I just found your website, it looks like an awesome collection! I looked through molly questions but couldn't find anything that answers my particular question, so here it is. <Okay> I have a black male molly and a red female swordtail in a small new 3 gallon tank. <Hard to keep such small volumes stable... do be diligent re maintenance... weekly water changes (maybe a gallon) and careful re feeding> I bought them a month ago and so far they've been getting along fine, mating and all. The female got pregnant and today started giving birth, and since she has been doing that, the male has been viciously attacking her! I've had mollies and swordtail fish before, for years, and know what they look like when they're horny or mating... and that was not it. The male would charge at the female in short, fast bursts and bite her. <Likely simple territoriality at play here... not enough room...> She'd dart away and slam into rocks, walls, etc. It looked pretty bad, so I isolated her in a smaller tank <! Needs more room, not less...> to have her babies in peace. Since I did that, the male has been acting normal. She hates the small tank though (about half the size of the other one, so not too small), and is flinging herself at the walls, so I may try to put her back again tomorrow. I've never had males attack females like that before, in labor or not... What's going on? I don't want to stress her out and am afraid to bring her back now :( Please help! Thanks, Didi <These fish need at least ten gallons... Bob Fenner>

Mollies beh. -- 03/17/07 Hello, <<Hi, Bridgette. Tom with you.>> We bought a male and female molly three months ago. Recently the female has been chasing and nipping at the male. Today she had 12 babies and is REALLY chasing him around. What should we do? <<Isolate the fry, if possible, and try to keep the adults separated. Mollies aren't 'protective' parents like Cichlids are even though it may seem like the female is guarding the babies and she's also stressed from the birthing process. She needs some recuperation time away from the male. (Sounds to me like she may be more 'dominant' than the male anyway and isn't about to put up with any of his unwanted advances right now.) You might try purchasing a divider for your tank at your local LFS to keep the two apart for a few days. If the fry can't be isolated, you can try purchasing floating plastic plants for them to hide in or, you can let Nature take its course. For what it's worth, you can start looking for more fry in about a month or so. Females can store the male's sperm for months and will continue to become pregnant even without mating during this time. Good luck. Tom>>

Balloon Molly beh.  3/10/07 <<Hi, Lauren. Tom here.>> I have a balloon molly who has recently been exhibiting some strange behavior.  Every once in a while she turns vertically, with her head pointing straight up.  It appears as if it is done intentionally because it is an extremely fluid movement in which turns horizontally, hangs out for a second or two and then returns to her typical horizontal swimming position with ease.  I have never seen her, nor any of my other balloon mollies exhibit this action.  I know that balloon mollies are odd little fish, but this seems a little too odd. Any suggestions as to what could be causing this behavior? <<Lauren, I've got an Angelfish that does this when it 'thinks' it's feeding time. If I catch the behavior in its entirety, my blood pressure remains normal. When I spot the fish 'floating' in this position, my blood pressure jumps about 20 points. A little tough on me and amusing to the fish, I'm betting. Fish, like other animals, tend to be extreme 'creatures of habit'. They don't 'think' in human terms but can 'associate' a behavior with a positive result, typically getting fed. I'd wager that your Molly is going through this routine because it associates it with finding food coming its way. Since it doesn't display other signs of a swimming impairment, I wouldn't concern yourself. Just look at it as an 'eccentricity'.>>    Thank you, Lauren <<Glad to help, Lauren. Tom>>

My Molly Changed Colors   2/14/07 Hello -   I have 3 Dalmatian mollies I purchased about 2 months ago.  One was a bit darker than the others but has since turned completely black. <Happens>   One of the others is also getting darker, but still has some white spots.  The third doesn't appear to have changed color at all.  Is this normal? <Not atypical> I have a few other fish in the tank as well, although the darker molly is surely the dominate <dominant> one in the tank, but everyone otherwise appears happy and healthy.  I feed them a varied diet and always add a bit of salt to the water, so I'm inclined to think there are no health issues, but I've never heard of such a thing before.  Is this a common trait with the Dalmatians or an indication of a bigger problem?   Thanks in advance for your insight! <Likely not a worry. Bob Fenner>

My Mollies  2/12/07 Hello, <<Hello, Ashley. Tom here.>> I recently bought some mollies, like yesterday. <<We'll count yesterday as 'recent'. :) >> I bought two Dalmatian mollies (1 male and 1 female) and 1 female Creamsicle molly. I have them in a 10 gallon tank with an angelfish a bit bigger than a loonie (Canadian $1 coin) plus fins and an itsy bitsy catfish which I can't remember what the exact breed is ( I think it started with an "o"). <<The 'itsy bitsy' catfish is an Otocinclus. The Angelfish will outgrow your ten-gallon tank just as a 'heads up'.>> From what I've read on the site the male is supposed to be chasing the females around. That seems to be the opposite in my tank. The Dalmatian female is chasing the male around. Is she trying to get him to mate with her? <<Nope. She's just more 'dominant' than he is. Not 'typical' but hardly uncommon.>> I've looked on both of the females and neither seem to be pregnant at the moment because I don't see a dark spot or anything but I also may have missed it. I'm not the most experienced. <<None of us were at the start'¦>> I also have another question about my Creamsicle one. It seems to be much more active than the other two, not that the others aren't active, the orange one's just more active, constantly swimming laps around the tank. I read about the whirling disease on your site, could this be an indication of this? <<Unlikely. Could be a sign of stress, though. Keep in mind that Mollies prefer some salt in their water. I would typify them as a 'brackish' water species meaning that they (generally) fall between true freshwater and saltwater. You'll find folks keeping them across the spectrum regarding salt however, from freshwater to full marine conditions. The sticky part is that your Oto won't tolerate salt well. What to do? Scaleless fish like your Oto can tolerate minimal amounts of salt. Never more than a ratio of one tablespoon per five gallons of water. On your next water change, pull out about two gallons of water and add about three-fourths of a tablespoon of aquarium salt to the new, conditioned water. This ratio won't adversely affect the Oto but might calm your Molly down a bit.>> She still moves around all over the tank but she also tends to backtrack often. So anyway, while the Dalmatians are playing tag the angel just sits around like usual, the cat fish sits in his corner and the Creamsicle swims laps. Can you tell me if they're exhibiting normal behaviour? <<Neither the Oto nor the Angelfish are particularly active individuals so I'd say their behavior is normal. The Dalmatian Mollies? Once again, their behavior isn't uncommon. As far as your 'Creamsicle' Molly is concerned, let's see if the salt does the trick for her.>> Also can anyone tell me how to determine the sex of an angelfish? I've had mine for four months now and have coerced her into being female calling her Morgaine, but I'm still curious if I got it right. <<Nearly impossible, Ashley, even for folks that are hardcore breeders. The common practice is to select a half-dozen Angelfish and see which ones pair up. From there, the one that lays the eggs is the 'girl' fish. Just about the only way to tell.>>   Thanks a bunch! Ashley <<You're welcome, Ashley. Best regards. Tom>>

Mollies Shaking - 01/27/2007 Hi <Hello.  Sabrina with you today.> We have a 40 Lt tank, with guppies and mollies. Most of the fish were born in our tank. Two of the black marble mollies (I think females but they are still a bit small to be sure) have this weird behaviour, they swim to the bottom section of the tank, in the corner and face down they shake their bodies - this can last for about two to three minutes a time and they do it approximately every 5 -- 10 minutes. They appear otherwise healthy, as do the other fish in the tank. What could be the reason for this behaviour? <In my experience, this "shimmy" has usually been indicative of a "skin slime" parasite - Costia, Childonella, Icthyobodo....  Other symptoms, though harder to see, would include occasional clamping of the fins and a slight "film" or "cloud" to the skin and fins.  I have also been of the understanding that this "shimmying" can be due to a lack of electrolytes or salts in the water.  If guppies and mollies are all you have, I'd try adding one to two tablespoons of aquarium salt per five gallons of water (12 to 24 grams per 19 liters).  This amount of salt will not be harmful to either guppies or mollies and will actually be quite beneficial to both.  This *may* also help if it is in fact a "skin slime" parasite, but if the symptoms persist after some days, or if the symptoms worsen and the fish get notably "sick", you might consider treating with an anti-protozoan medication.  Of course, this part goes without saying, but I'd better say it anyway:  Be sure to keep ammonia and nitrite at ZERO and nitrate below 20ppm with regular water changes.> Thanks for the great information you supply on your site. <I'm glad you've found it useful, thanks!> Steph <All the best to you,  -Sabrina>

Molly at bottom of tank   1/23/07 Hi Guys <LJ> I have a question about my male Dalmatian molly. First, we goofed up and overcrowded a 5 gallon tank with 2 Dalmatian mollies (1m, 1f) two black big bellied mollies (1m, 1f), and one white big bellied molly. We also have a Pleco,  <Need much more room to keep one of these> a catfish, and 4 big snails. We tried having an African Dwarf Frog, but the ammonia levels killed off 1 then because we didn't know what killed it, also the  replacement frog. While still in the 5 gallon tank, the male Dalmatian molly started swimming at a 60 degree angle, head up. Sometimes it would go completely vertical. He then started just hanging out at the bottom of the tank. Almost lying in the gravel. We were unable to keep the ammonia, nitrate and nitrite levels within healthy bounds, so we got a 20 gallon aquarium and moved them all in there. <Much better> He's  still lying in the gravel. <Takes time... might be damaged> Sometimes he seems to get a burst of energy and swims  around a for a while. He doesn't seem to have a lot of control, and tends to be  a little "head up". The ammonia, nitrate, and nitrite levels in the new tank are  okay. But, I don't know if there is anything we can add to help the poor guy, or  if he's just gonna die. Any suggestions? <Patience, time, observation, hope. Bob Fenner> Thanks ---Linda

Molly behavior - why do they act the way they do?  1/14/07 Good morning WWM crew! <Good afternoon now...how are you?> Yesterday I entered into the world of "Molly Hobby". I acquired 5 Mollies and one sucker fish (Jock). <The latter, is it some sort of Pleco? If so, be aware that the common variety of these can grow to over a foot in length...do be prepared to provide a large tank for him/her...> The mollies are as follow: "OJ" (orange M) "Goliath" (White/Silver M) "Flo" (Dalmatian F) "Perdita" (Dalmatian F) "Baby Pearl" (White/Silver F) <Sound nice.  If you have space, you may want to add a few more females; I've found a 1:3 or 1:4 male: female ratio to be best, to prevent over-harassment of the females by the males...> I am fascinated by these fish's behavior! I can sit in front of the tank for hours just watching them. <They are quite interactive, aren't they? I enjoy watching mine as well...and since they are always looking for food, they seem to "watch" you back, don't they?> During my observation, I noticed something. The two Dalmatian girls look to maybe be pregnant...they are a lot 'rounder' than the White/Silver. I research to find out how to tell and of course they should have that black spot...can't really tell w/ the Dali girls. <Yes, can be hard to tell with the Dalmatian coloration. Generally, when you have both male and female livebearers in a community tank, the girls will likely be pregnant...that's what these fish do!> The white one should be obvious and there are no darker areas on her. <She may be "early-stage" pregnancy.  All you can do is wait and see; molly gestation period is about 4-6 weeks. Again, my bet is on all the girls in your tank are indeed preggers...they virtually always are!> Once all the fish became 'comfortable' in the tank they started moving around. It seemed the two Dali girls were trying to get the attention of the two males but they didn't want anything to do with them. <Interesting - it's usually the opposite!> Instead, both the boys were after the white F. I saw both the males mate several times and can't seem to get enough. The two boys even pick at each other. All this is happening with the Dali girls being left out. So, what is so special about "Baby Pearl"?? Sometimes she likes the attention and other times she seems annoyed; in addition, the two dalis seem to 'protect' her sometimes and they seem to be jealous other times. <I can't tell for sure what the fish are "thinking", but again, if you have room, increasing the amount of females in the tank should help re-direct some of the males' attention.  Perhaps the two "left out" girls are already pregnant, and the little female is not, so the boys are trying to change that? Or, something in Baby Pearl's temperament attracts the boys...can't tell you for sure.  Just make sure to provide lots of cover in the form of plants, decorations, etc., so that any one molly can "retreat", if need be.> My sister, an advanced hobbyist, really couldn't come up w/ anything except the two dalis are already pregnant and "Baby Pearl" is a virgin so to speak!!! <That's what I'm thinking...but it truly is just an educated guess.> Please help me understand my mollies behavior! <I'm not sure anyone really "understands" fish behavior completely; it's likely natural selection, Darwinism at work...> Thanks, Stephanie <Stephanie, the only thing I can suggest is altering the male: female molly ratio a bit, to spread out the aggression of the males a bit.  Again, this is assuming the tank is large enough and not already fully stocked... Enjoy your mollies - they are fun little fish! Best regards, Jorie>

Molly Gender Changing   12/6/06 Hellow WWM crew! I used to have a few mollies, and I have a very strange question about one of them. We went to a pet store, and I'm pretty sure we bought a girl Molly. (The guys have this little stick fin thingy, and the girls just have regular fins.) <Ah, yes> Well, we got home, and she was so fat, she almost looked pregnant. Well, about a week later, I noticed some spots on her. I didn't think it was such a big deal. So the next day or so, we went on vacation to Florida. By this time, the fish was half covered with spots. So when we came back 2 weeks later, the fish had changed into a boy! Or at least I think it was a boy! <Mmm, yes... happens> She had spots everywhere, and she was a BOY! I even caught her trying to mate with other girls, and if I'm right, got one of them pregnant. Is it common or at all possible for a fish to just change genders like that, or do you think maybe he was a boy the whole time? <Could be either... not uncommon.> I'd love to know! (The fish is dead now...been dead for 2 years...just thought I might add that on.) Any help is appreciated! Thanks WWM crew! -Leira <Want to be further astounded? Look up "Amazon Mollies"... Bob Fenner>

Molly Mayhem  11/21/06 Hello, <Hi> I stumbled on your site, looking for an answer to my question, and could not find it, so, so I am asking... <Ok> I bought two Dalmatian Mollies about a month ago, and added them to a 55 gal tank with Neons, two Powder Blue Gourami's, one Silver Shark, and two Dinosaur Eels.... ok, now before you tell me, yes, I know the Eels should not have been in there, and we found this out by losing a few fish, they have since been separated into another tank of their own.... <Several of the remaining fish come from very different environments and require different water conditions, check out WetWeb for specifics.> Anyway... before our Eels got really "hungry" all of a sudden, our female Dalmatian looked as if she were getting quite plump, so we thought we were going to have fry soon... then our eels did their thing, and we lost our male Dalmatian, a few Neons, and two blood gourami's, and a powder blue Gourami... after this happened, and we removed the eels immediately, our one powder blue, and our female Dalmatian started acting like they were really confused, they would swim all over the tank, very rapidly, as if they were "looking for something" during this time our female Dalmatian seemed to "lose" her plumpness, and we just wrote it off that she was not pregnant, because she never got big enough to "drop"... <Not uncommon, she probably either gave birth prematurely or aborted the pregnancy altogether.>  So we went and bought another powder blue Gourami, and another male Dalmatian, and added them to the tank.  Both "stressed" fish calmed right down, and "buddied" up to their new friend... and we seem to have happy fish again, (and our silver shark is now growing, which he wasn't doing before)... but the main question I have is this... now it seems that our female is getting quite plump again, and the male and female, who were getting along great, now are exhibiting behavior I do not understand. I read that when a female molly is pregnant, she will irritate others in the tank <Depends on the individual>, but this is not the case, it is quite the opposite, the male molly follows her constantly, seeming to "smell" her rear side <Trying to mate.>, and she is constantly trying to swim from him. He does this all the time, seeming to give her no peace at all... what is the deal with that?  <Need to have more females than males to give the ladies a break from the very determined suitors.>   She is not bothered by any of the other fish, they all seem to get along very well, we still have the two powder blues, 3 Neons, the two Dalmatians, and the shark, along with a plecostomus. I was trying to look for the black spot they speak of, and the problem is that she is so dark black, with Dalmatian spots, that we can't tell... any help? Thank you, Kathy <You can assume she is pregnant, they almost always are if they are in contact with a male within the last 6 months.  The harassment is normal, and can be lessened by adding more females if the tank size allows.  You need to review the requirement of your various fish for incompatibilities and the long term problems that will develop from them.> <Chris>

Male Molly behavior  - 10/17/06 Hi <<Hi, Jessica. Tom>> I love your site; all your information is great. Use your advice daily for my aquarium. <<Thanks, Jessica. Nice to hear we've been of help to you.>> Searched for this answer, but no luck. <<That's why Bob has this feature on the site'¦>> My male gold dust molly has started to go crazy with the submersible heater. His entire body wiggles rapidly back and forth and his mouth brushes the side of the heater...? Almost looks like he's kissing the heater. He does this for a while; doesn't seem to mind other fish by the heater. Any thoughts as to what this could be? Is he ok? <<Well, Jessica, he's'¦'different', I'll give him that. If he were trying to make out with a mermaid decoration, I could understand but this is a bit unusual. Actually, I think he's sensitive. Very sensitive, in fact. Heaters in our aquariums operate like toasters. The wiring has a high resistance to the flow of the electricity which causes it to become warm, or hot, as the case may be. So far, so good. The flow of electricity also creates a magnetic field around the wiring which is how an electro-magnet works. Wrap wire around a common iron bar, turn on the 'juice' and the bar becomes a magnet. (For those taking notes, this is the principle for solenoids which operate water valves, electric latches on locks, etc.) 'Where is this taking us?', you ask. Fish have what is called a 'lateral line' along both sides of their bodies which aids them in, basically, sensing what is going on around them. What they might not see or smell, they may be able to 'feel' through these linear sensors. My guess, and it's only that'¦a guess, is that your Molly is picking up on the minute magnetic field created around the heater and, he likes it or, at least, he's curious about it. I don't think he's got a real good idea about what it is but the 'wiggling' tells me he's picking up on something and 'mouthing' it makes me wonder if he thinks it might be something edible. Frankly, I'd be interested in knowing if replacing the heater changes his behavior.>> Thank you Jessica <<Interesting question, Jessica. Thanks for writing. Tom>>

Male Molly Behavior - 10/18/06 Tom, <<Hi, again, Jessica.>> Thank you for the fast and informative reply. It's much appreciated. <<Happy to have helped.>> I just bought another small heater for my 30 gal. tank just in case our Minnesota winters are too much for the other heater. Anyway, after reading your response, I unplugged the original heater and Mr. Gold Dust Molly stopped his wiggling and kind of went, "huh?" Then immediately swam away to the new heater. <<There's Mollies for you. Absolutely shameless...>> After checking out the new heater, he returned to the original. <<Guess the grass wasn't greener, after all, eh?>> All I need is some goofy fish attached emotionally to a heater...haha. I decided to not break his heart and plugged the original heater back in. We're back to happy wiggling. Oh brother. <<And I just finished posting to another reader that fish don't need to be "entertained". :) All I can say is that I hope for a long and happy life for your Molly and his heater! Thanks for writing back.>> -Jessica <<Tom>>

Rogue Molly beh. mod.  9/28/06 Sorry, I couldn't find the answer in a Google search or in FAQ's.  I have a standard 30 gal freshwater aquarium, running well.  I've had the same mix of freshwater fish for quite some time, tetras, Chinese algae eaters, catfish, swordfish.  I have one male molly that has become a terror in the tank, always chasing the other fish and now they huddle at the bottom. <Likely time for him to go...> How do I get rid of it, short of flushing an otherwise healthy fish ( I don't want to kill it) and the local store won't take it back? (Been too long) Thanks, Gina Sulmeyer <Mmm, another tank?... But, there may be some "behavior modification" that might be done by giving this fish a good "time out"... netting it, keeping it in either a breeding trap or small floating plastic colander (check with the significant other first...) for a few days... often this sort of separation "knocks the perpetrator down a few pegs". Bob Fenner>

Vertical Mollie?   8/18/06 Hi <Hi Alex, this is Jorie.> I recently bought a couple of Mollies (1 male, 1 female) and set up a 10 gallon aquarium which seemed to go really well. today I added a couple of guppies. After 1/2 hour or so I noticed that the female molly is swimming almost vertically, nose down. The male seems to be fussing around her and nuzzling her. Is anything wrong? <If you haven't already, you should test the water parameters, including ammonia, nitrite and nitrate.  How long has this tank been established and what type of filtration are you using? Has the tank fully cycled?  A bit more information would be helpful. Also, with regards to livebearers (both mollies and guppies), it is not typically a good idea to have a 1:1 male:female ratio, as the girl will usually get very harassed by the male.  Having said that, I'm not suggesting you run out and immediately buy more females - are the four fish you mention above the only ones in there?  *If* the tank is established (i.e., cycled), then I would suggest perhaps adding a couple more girls, or perhaps even swapping the male for a female, if possible.  You do realize that livebearers, especially mollies, seem to reproduce exponentially - have you figured out what you are planning on doing with the fry? Do take a look here for detailed information on all things pertaining to FW aquariums: http://www.wetwebmedia.com/FWSubWebIndex/fwsetupindex.htm > Thanks for the help, <Hope I have helped. Jorie> Alex

Spinning molly!  7/15/06 Hi <<Hello, Jan. Tom>> My son has a lovely tropical aquarium but he has a problem with one of his Lyre tail mollies. It keeps spinning. He keeps his filters  maintained and does his gravel washes approx every 8-10 weeks, the rest of his fish have no problems at all. Can you tell me what might be wrong with this one particular fish, please? <<Jan, this behavior occurs when a fish has developed an internal infection/infestation that causes its body to "contort" to the degree that it can no longer swim in a straight line. The most notorious example of this is referred to as "Whirling Disease" which is caused by the sporozoan Myxobolus (Myxosoma) cerebralis. This particular sporozoan invades and resides primarily in the animal's spine creating a curvature that results in the "spinning" activity you've noted. Sadly, there's no cure for this and the fish should be isolated. I can't tell you with absolute certainty that your son's Molly has developed Whirling Disease but I do cite this as a possibility. Finally, if by chance, your son feeds his pets Tubifex worms, have him stop immediately. These creatures are known to feed on bacteria and are not recommended as they have been connected with bacterial infections in fish including Whirling Disease in salmonids (salmon, trout, et. al.).>> regards Jan <<Best of luck. Tom>>
Re: spinning molly!
 7/15/06 <<Hi, Jan. Tom again.>> Thank you for the rapid reply. I'm just pleased to know what the problem might be. I will pass this information on to him. <<Please recommend to your son that he keep a close eye on the rest of his pets and keep his aquarium conditions as optimal as possible, as well. Many, if not most, of the pathogens we commonly run across in the hobby are "opportunistic", seeking out stressed fish. Excellent water quality is crucial to maintaining a stress-free environment. Far easier, as you might imagine, to handle a little extra "housekeeping" than to deal with sick livestock.>> Many thanks Jan <<Happy to help any time. Tom>>

Molly problems 6/14/06 Hello, <Hi> I am a bit of a beginner when it comes to keeping fish.  <We all were at some point.> The tank was have is rather a small one, but ideal as we are still beginners.  <Actually, bigger usually means easier.> The white Molly in question was purchased about 2 and 1/2 months ago and was in good health at first. Then about 5 weeks ago it seemed to become kind of deformed in shape, its stomach area became really round and looked black inside. Then it seemed to be having trouble swimming and was only using its side fins, not its tail. We have been keeping a close eye on it, but as it always seemed to be feeding we didn't think that whatever was wrong was that serious. This past weekend we have been away and when we came back I looked in the tank and the said Molly is now a 'normal' shape and swimming fine, but it looks about half the size of the other silver Molly we have. Could it have been an illness that it just got over itself?  <Always possible but doesn't sound likely.> Or is it possible that it could have had babies?  <Most likely scenario.> I have looked at some of the frequently asked questions on your site and read that Mollies are usually pregnant for about 32 days, from working my math out it would seem the if ours had of been pregnant that would have been a lot longer than 32 days. Any light you could shed on this would be much appreciated. <Well, with live bearers it is never that simple.  Their method of reproduction puts rabbits to shame.  Mollies actually have the ability to store sperm for up to six months, then become pregnant when they feel like it, which is usually quite often.  So while gestation is around 32 days or so, the actual insemination of the female could have taken place months before.> Do you reply to this email or post it on the website? <Both> Thank you. Shelley <Sounds like you have a typical molly, expect similar behavior in the future.> <Chris>

Black Balloon Molly   5/14/06 Hi <Hi - this is Jorie!> I have a 71 litre tank with 11 Tetras, 3 male guppies, 1 Balloon Molly( lost her mate) and two bronze Corydoras. <According to my math, this is about 18.75 U.S. gallons...you are very well stocked, so do be sure to do regular, substantial water changes (e.g., 50% per week)> My Molly is attacking the black male guppy constantly, nipping at his tail. Why would the Molly attack only this one other fish? <Livebearers do get territorial sometimes, and it's hard to determine exactly how they choose their foes.  Be sure there are plenty of hiding places in the tank.  Ultimately, if the behavior continues, you'll have to remove one or the other...perhaps the molly could go into another tank somewhere?> I did have a Platy in the tank but had to put it in my other tank as the Guppies were attacking it. <Again, livebearers will do this to one another.> I don't really want to have to move the Molly <You may not have a choice.  What is the other tank's set-up like?> Is this too many fish for my tank? <It's definitely at max. capacity.  As long as you keep up on the water changes, provide enough cover for the fish, and everyone seems healthy, you may be OK.  How long has the setup been like this?> Ty <Welcome.> Caroline <Jorie>
Re: Black Balloon Molly
- 05/16/2006 Thank you for your reply. <You're welcome.> The Tetras I have in the tank are small, as in Neons and Glowlight; do you still think this is too many fish for this tank? <As long as you keep up on your husbandry, you should be OK.  I wouldn't suggest adding any more fish however.> I do a water change at least once a week and sometimes two. <That's great - this is truly the best preventative maintenance/medicine!>   I have two filter systems in tank an under gravel and Fluval underwater filter. Tank has been set up like this for 4 months and all does seem ok apart from the Molly being a bully. <Sounds like a good setup on the whole.>   I have noticed today that she is at times chasing all the other fish so guess I may have to move her. <Sometimes this is the only solution with an aggressive, territorial fish.  Plus, if you just have the male livebearers (e.g., guppies), you won't have to worry about the multiplying factor, as it can quickly get overwhelming!> I will make sure there are plenty of hiding places. <This will help.  Perhaps try adding some spots before resorting to moving her...> The other tank set up I have is a Biorb, which houses 6 Neons, a Platy and two Albino Corydoras Catfish to keep the bottom clean. I also do a water change in this once a week. I am worried about putting the Molly or Guppies into the Biorb for fear of overcrowding. <From what I can tell, the "Biorb" you refer to is 30 litre, or approx. 7 U.S. gal.  It doesn't appear from the picture I just looked at that there is filtration in there, so I agree - probably not a good idea to add anyone else.  Do keep up on the water changes.> Thank you for your advice. <You are welcome.  Try adding some decorations and fake (or real, if you are so inclined...lots of fun gardening underwater!!> plants for cover to see if this alleviates the bullying problem.  You could also try re-arranging any existing decor you have - any "territories" that the current residents have staked out will then have to be re-arranged.  This can sometimes help in situations of bullying fish.  Best to you and your fishies! Jorie> Caroline

Molly and Platy Behaviour - 05/06/2006 Hi there, <Hi - you've got Jorie here tonight> I don't know what to do with my fighting mollies & platies. I have a 10g tank.  I had 1 male platy, 1 unknown platy (no female or male fin), and 1 female black molly.  I wanted to breed the fish, so I bought a black lyretail molly back in February.  The 2 mollies have been getting along all right...although he chases her incessantly. <Livebearers, esp. mollies, are notorious for this.  Generally, you should keep a 1:4 or so ratio of males to females, or the males will likely bully the females to death...> About a month ago, I bought another male platy (thought it was female, but just not developed yet).  The new male platy is somewhat aggressive and will not let the other male near the "unknown" platy.  There was a lot of fighting starting and fin nipping, with my original male platy starting to hide out, so I moved all 3 platies to my 35g tank.  I thought having more room and being in a different setting might change things a little (take out some of the aggressiveness in my new platy).  Didn't work.  So, then I moved my original male platy back to my 10g. <You said "you moved three platies".  Bottom line is you have too much testosterone in that tank! With a 10 gal. you really should only have 1 male livebearer in there, with perhaps 4 girls.  What all do you have in the 35 gal.? Perhaps the male molly can be moved there?> Now, in my 10g are the 2 mollies and 1 platy.  Yesterday, I noticed that the mollies were starting to fight with each other.  I thought this might be some kind of mating behaviour, but after today I'm not sure.  The male molly is constantly following the female around with his mouth sniffing?? nipping?? at her belly. <That's what the boys do to the girls...all day long.  This is why you can't have a 1:1 ratio> But yesterday, it's like she had enough.  They curve their bodies and swim in circles nipping at each other.  A few times, I saw (seen?) the female grab hold of one of the male's fins and not let go...dragging him and jerking on him. Before the 2 fish decide to kill each other, I moved the male molly to my 35g today. <Perhaps you can just have a few females in the 10, and put the males into the 35...> So, now I have a female (bullyish) molly and a skittish male platy in my 10g tank, <I'd watch this combination closely> and the male molly, male platy and unknown platy in my 35g. <Sounds good.> Any ideas on what kind of behaviour is going on here? <Yes - horny male livebearers! This is what they do...>   Why would this aggression start now...after being together for 3 months? <Perhaps they weren't sexually mature until recently.>   I'm not sure where to move what fish and how to possible get any of my fish breeding without overstocking my 10g. <Your livebearers will breed wherever, whenever, so don't worry about that! But, whether or not the fry will survive depends on what else is in the tank.  I don't know what all you keep in the 35 gal., but perhaps let the fish you want to reproduce be in there, and make sure there's plenty of hiding spots for the fry, incl. floating plants if possible.  Also, you could catch the fry as soon as you see them born and let them grow in the 10...I did this for a while playing the game of "musical livebearer tanks...Bottom line, you cannot have more than 1 male livebearer, molly or platy, in your 10, and you need to have a few girls in there so that the sexual aggression is fairly spread around.  Even Also, make sure there's ample hiding spots.  Alternatively, and probably the better idea (as mentioned above) consider just keeping females in the 10...trust me, if you have a few girls in there, it won't be long until you see fry, as the females can hold sperm up to 6 months!> Help please!! Donna <Hope I have! Best of luck, Jorie.>

Molly and Platy Behaviour - 05/07/2006 Thanks for the super quick response! <You're welcome - we try our best!> What do you mean by watching the male platy and female molly??   <I just meant to make sure the "bully" female doesn't go after the "skittish male"...just to keep an eye on everyone, which you already seem to do!> Until I can get some female platies to add to my 35g, I don't want to move this platy because the other male platy is nipping at him. <You should be fine - I was only concerned because of how you described the two fish you currently have in the 10 gal. respectively as a "bully" and "skittish".  As long as there is no aggression, everyone should be fine as is for the time being.> In my 35g, I have 2 penguin tetras, 1 white tetra, 1 pleco, 1 snail, 10 neon tetras, and 10 harlequin rasboras, a lot of artificial plants, and a few rocks. <Sounds good - pretty small fish with lots of swimming room I am sure they appreciate!>   I plan on eventually changing the substrate in this tank to fluorite, removing everything artificial and adding live plants, more rocks/caves, and a couple "centerpiece" fish as recommended by someone else on your site the other day.  They suggested either German Rams, Kribensis, and/or Cherry Barbs. Although, I'm not so sure about some of these with the mix I have. <The barbs could potentially be problematic, but the rams are peaceful, not to mention bright and colorful.  Just be sure you have provided lots of hiding places and plant cover for them, if you go this route. The Kribensis a/k/a purple cichlid a/k/a pink cichlid is also relatively peaceful, so that should be OK as an alternative "centerpiece" fish.> I had originally wanted to go with 2 clown loaches, but was told they would be too big for this tank. <OK - I think I was confused and thought the clown loaches were already in the tank.  Yes, I agree on them truly being too big for a 35 gal. - they can grow over 12" long...> Donna <Hope I've clarified things a bit. Best regards, Jorie>

White molly circling  - 4/3/2006 <Tom> We have 11 mollies in a 20 gallon tank.  We were advised by the pet store to have 10 maximum, but one of the 11 is medium small (younger).   We also at this point have a rectangular netted cage hanging in from the top with about 40 babies in it that recently were born.... Today one of the mature white mollies began circling over and over. In one little spot she just goes round and round.  She now has positioned herself near the air bubbler and is still making these small circles.  We believe all the adult fish are females.  Is this fish feeling crowded out all of a sudden and is getting territorial or what? Thanks... (a few of this fish are a rather large size...maybe 2 or 2.5 inches.) <To be honest, I don't know that there is one "best" answer to your question. Mollies can have multiple, viable pregnancies from a single mating. If she's pregnant or, "thinks" she's pregnant, her behavior wouldn't be unusual, most particularly if she were close to giving birth. Her "circling" doesn't suggest, to me, the type of swimming behavior that we normally associate with a "stressed" fish. If she's feeling territorial, it seems to be with some other purpose since I don't infer from your post that she's "defending" her area of the tank. Tom>

Weird molly behaviour  - 03/27/06 Hello! <Hello! Tom here> I have written to you guys before and found you to be very helpful. <Glad to hear we've been of help> Currently, I have just given away approx. 6 fish from my tank, leaving a mother molly (I gave away the babies when they got bigger, plus the dad) and a Betta and a Chinese algae eater. <Wish you would have given away a "seventh", the CAE> My mom molly (Gold Dust) has been swimming very weird in the last day. She has been hiding in the rocks and helmet in my tank and when she does come out to eat or swim she sort of flips over or swims very oddly from side to side, like she is rocking. I can't really describe it, but I hope that description has helped. <I have deep suspicions...> Is this because she is lonely or stressed or sick, etc?? Thanks! - Heather (P.S. I plan on getting a couple of more non-molly fish. Any suggestions? I have a 10-gallon. Thanks) <The only suggestion I would make right now is to get rid of the Chinese Algae Eater immediately, if not sooner. These fish grow large, become aggressive/mean as adults and are known well to feed on the skin of other fish. Not a pleasant creature and I wish they weren't sold as pets. I wouldn't discount this fish's possible aggression toward the Molly as an explanation for her "weird" behavior, especially the hiding and/or any possible physical damage done to her. That said, you're going to have to do some "homework" here on potential tankmates. Mollies tend to prefer some salt in their water. Bettas don't. Your options would be greater were you to move the Betta to his own tank, preferably one with a heater. This would give you some "latitude" in your choices for your Molly's tank. When you've done your research, go with what appeals to you. (Personally, I don't want someone else "decorating" my house. ;-) Tom>  

Strange Molly Behavior and a new tank   3/10/06 Hi again! Thanks for reading another e-mail. Ok just wanted to say I recently got a new ten gallon tank that I am extremely proud of. It contains one live plant an Anubias and four bulbs of Aponogetons. <Really neat plants> 1. Cory 2. Ghost Shrimp 3. Mollies 3. Platies 1. Sucker fish 2. Goldfish <Mmm... too "different" to go here. Best not to mix with tropicals...> 3.Guppies I love them all too death and I am happy to say nothing in that tank has died yet! Ok my questions I think will be easy, and I hope you can answer them or if they have been answered I hope you can tell me the specific page to look cause I probably missed it. I have as said last time two female mollies one that is absolutely gorgeous yellow with darker yellow spots and one that is larger a molted female, I recently acquired though a male a Dalmatian lyre tail a pretty little thing. Ok The bigger female molly started chasing my smaller female as soon as I got them and had them in a one gallon tank. I thought it was just a space issue and it would stop once they were moved to their new quarters. The yellow female was still being chased and then to my horror I saw that her dorsal fin was missing like the top half the tiny bones sticking out! I am positive that it was the other female. Today I noticed two roundish pink spots like she was missing scales or had been bitten. So I moved her to the one gallon I put the two gold fish with her as well so that she is not alone. Was this a good idea? <The moving of the molly yes, but not with the goldfish> I think it might stop the stress of being out of the community tank. Still though she swims in place in the top of the tank in one of the corners. She has her fins tucked and her lovely color has significantly faded to a soft pale yellow. I don't know what is wrong <Physical trauma, stress> and I don't know what to do or try to stop this. Should I move her back to the community tank or should I leave her be? <Needs to be either separated or if with these other mollies, in a much larger system (at least 29 gallons)> She swims around every so often and she eats as she normally does so what do I do? Thanks for the help -Maria <Please read re Molly Disease on WWM. Bob Fenner>

Male Molly Behaviour 2/28/2006 I recently (2 weeks ago) bought two Dalmatian mollies and today I discovered one baby. After doing some research, I figure that I have a male and female. The male within the last two days has been swimming around with the female and keeps raising his top fin and fanning it out. I am just curious if this is mating thing or if it is normal behaviour? <<Is a way of showing off and establishing dominance.>> Amy <<Lisa>>

Molly mating behavior  - 2/21/2006 Hi there. <Hello> Can you please describe for me the mating behaviors of mollies?  I suspect mine are mating and was hoping you could verify. Thanks a bunch. Laura <Mmm, a bit of a dance with male/s pursuing females from behind, the side, and flicking their intromittent organs (modified anal fins called gonopodia) toward the vent areas of the female/s. Bob Fenner>

Black Molly Play's Dead   2/9/06 Hello, I just wrote in a short time ago, my apologies for not putting this concern in the first e-mail.  I have checked all over and this I have actually found no information on. I again have 5 fish, a black molly, and algae eater, a neon tetra, and the two guppies.  I keep all the ph levels around normal and the temp around 78. The Black molly will from time to time sit on a leaf or pin himself between the grass and the filter and not move.  He will not flip his front fins or anything, he just looks dead until I tap the glass and he swims away.  Do you know why?  Is this ok? Thank you again. Eric M. Becker <Likely nothing wrong here... mollies do "just rest" every now and then, as long as it "gets up" and has erect fins... I would not worry. Bob Fenner>

Google... mollies, chasing, hurting   2/6/06 Dear WWM,     I have recently bought 3 silver lyretail mollies(2 females -1 male), but one of the females  are chasing around the male and I don't know if it is either hurting it, or doing something else?                                                             Thank You, <... Google... mollies, chasing, hurting: http://www.google.com/custom?q=mollies%2C+chasing%2C+hurting&sitesearch=wetwebmedia.com Look at the cached results... Bob Fenner>

Molly trouble? Uncycled system, aggression  - 2/4/2006 Hi Guys, great site! I found your website while Googling on aggressive mollies, you see, the problem I have is this..... I just set up a 10g tank, my first. I asked the staff at my local pet shop what would be a good fish to start off with, and they recommended two mollies, since they are good communal fish, but get lonely on their own. <This system was/is cycled?> However, I had been doing some reading on cycling an aquarium, and decided to put only one molly in to start the cycle, so I bought one Dalmatian Molly. After a few days, I tested the water for ammonia and nitrate/nitrite, and everything was fine, <Takes a few weeks...> so I decided to add another Molly to keep the other one company. I bought a Leopard Molly, which is slightly larger. I realize now the cycle takes a bit longer than 3 days, but at the time I didn't and I wanted the Dalmatian to be happy. At first the Dalmatian Molly was happy swimming around with his new friend, but the next day, the Dalmatian Molly was chasing around the Leopard Molly. The poor guy cant get any peace, every time the Leopard Molly stops, the Dalmatian Molly swims rapidly towards him. It looks like he's trying to nip him. The attacks seem mostly to come from behind, but attacks from the side, above and below aren't uncommon either. I'm unsure whether they are male or female, but I'm pretty certain they are the same gender. Is this normal behaviour for Mollies, or is the Dalmatian just a bully? <Can be normal... but having them in small odd numbers, larger tanks generally alleviates> Id hate for the Leopard Molly to die of stress. I keep my tank at about 75 (although I've noticed this can fluctuate upwards to almost 80 when the light is on), <Too much diurnal flux...> with a little bit of salt and plenty of hiding places. Thanks Russell Gold <Likely all will be well here in a few weeks. Be careful re feeding, perhaps catch the bully and keep it in a net up in the corner of the tank for a few hours... this often works to reduce aggression. Bob Fenner>

Dalmatian Mollies behaving oddly   1/31/06 I have never owned Dalmatian Mollies before, and I just introduced four into a 12 gallon aquarium.  The aquarium has no other fish, but it does have established plants and has been treated and cycled. <Good>   The fish have only been in the aquarium a day and a half, so I expected a bit of stressed behavior, although they were behaving and eating normally yesterday.  Today however, one has started bouncing its sides off of a large smooth rock in the tank and they are all swimming pretty erratically (still eating though).  In addition, I noticed when I turned on the overhead light in the tank that they have iridescent yellow-orange spots on their sides. <These last are "natural"> I know that mollies interbreed so at first I thought this was probably just evidence of having golden molly ancestors, but I recently came across a description of velvet disease and I was wondering if this could be the case. <Highly unlikely... look much more like dust...> The temperature is 78 degrees and there are already 4 teaspoons of aquarium salt in the tank <Good> (I do not want to add more b/c I plan on adding Cory cats). Thanks. <I would just "hold off" and observe these fish at this point. They do "ship poorly" at times (and often all the way from the Far East)... and have troubles in adapting from systems with enormous microbial populations to cleaner water. You have done most all that is generally required (cycled, planted system, salt content). Hopefully these mollies will "settle in". In the event that there is a pathogen detected, I would look to Acriflavine and Malachite (both) remedies. Bob Fenner>

Dalmatian Molly swimming weird?   12/28/05 Hi, Great site amazing amount of information. I've been observing weird behavior with my Dalmatian molly, I have a 2.5 gallon aquarium with a guppy and a Dalmatian molly, three days after purchasing from Petsmart one of the fish had seven babies which I removed and put them in a separate bowl. I'm not sure which fish had the babies and now it has been 8 days since I purchased the fish and the Dalmatian molly is swimming very awkwardly. The dorsal and tail fin seem to be completely inactive, the fish is only using the fins on the sides to swim and the head of the fish is pointing up when moving. Also it seems to have a very small white fuzzy cotton looking thing next to the eye, not sure if it was there when I bought it although still a concern. I have tested the water and the nitrite levels were at 4.0 and ammonia at .5 so I changed 50% of the water which will hopefully bring that down. <Mmm, need to cycle completely... and quickly! Please see WWM: http://www.wetwebmedia.com/FWSubWebIndex/fwestcycling.htm>   If you have any other information to a diagnosis or cause or treatment I would really appreciate it! Dave <Your water is deadly toxic presently... and the Molly is a brackish water animal... You would do well to add a bit of salt... covered on WWM, and yes the Guppy will tolerate a moderate amount. Bob Fenner>

Molly Aggression  12/20/2005 Hello, <Hi Kara.> I recently found your website and find so much of the information helpful, thanks! <Quite welcome.> I have a question I am hoping you can help with. I have a 10-gallon tank, which I have had for about  8 months. I keep the temperature around 78 degrees. I do about a 1/3rd water change once a week and try to maintain a very clean nice place for my fish. <Glad to hear it.> I currently have 2 neon tetras, 1 red platy, 1 skirted tetra, 1 black and white molly, and a golden algae eater. <Lots of fish for this size tank.> Lately the molly has been acting more aggressively than he has before. <Some Molly have quite the attitude on them.> He chases the platy and skirted tetra around with more vigor. He appears to be trying to nibble their lower fins. <Quite normal.> Also, he has been swimming in circles around the skirted tetra while displaying his top fin with much finesse. Then at times he will just lie at the bottom of the tank under a bush. I can't figure out if he is lonely, or sick, or crowded. He used to just swim happily about. I have read that molly's like to be with fish of their species so I thought of getting a female molly for him but don't know if that would over-crowd the tank or make matters worse, make him more aggressive. Any thoughts you have on this subject are really appreciated. <I wouldn't add any more fish, I would actually consider removing the molly, sounds like he is becoming territorial due to overcrowding. I would remove him.> Thank you, Kara <Your welcome, Adam J.>

Re: Molly Aggression  12/24/05 Hello again, <Hi Kara.> just wanted to say thanks so much for the really helpful and fast response. It's important to me that my fish are happy, so thanks for your help! You guys are great! Kara <You are welcome and thank you, Adam J.>

Molly Longevity, Useless False Info - 11/10/2005 Yes, When I purchased my mollies at my local pet store the so called "fish expert" informed me that female mollies die after three births. <Uhh, what?  What was he smoking?  I sure don't want any.> After, reading your site I think this must be absolutely absurd since you say a molly can continue to have births for six months without a male. <Entirely possible.> Am I correct in assuming this was false and useless knowledge? <False, for sure.  Useless?  Um, no, most any tidbit you get from anyone isn't quite "useless"....  See, in this case, you found (I hope) that you can/should verify information from sources of unknown quality with other sources.  Even us; don't take any one source as undisputable truth.> Also, how long can a well cared for molly be expected to live? <Perhaps a few or a handful of years....  many months at the very least.> Thanks,  -Amanda <Wishing you well,  -Sabrina>

Molly Behaviour / Aggression - 11/01/2005 Hello again. I wrote the other day about my male molly claiming the heater. I think I know why. My three Dalmatian mollies are very aggressive toward him. They will not let him eat; he has to wait until the food sinks. I was wondering is this normal for the females to be so aggressive towards the male? <Mm, usually it's the other way around....> He is quite a bit smaller than they are. <This could be contributing to it.> I'm just afraid he's not getting enough to eat. Plus I'm pretty sure all three are pregnant, they are getting big bellies. Could this be why they are so aggressive? <Quite possibly.> Also I have balanced my ph finally at 7.8 and have been checking it every day. <Ah, good!> Sorry to bother you again but I've been reading through you're site and can't seem to find this problem. <No worries. Give this some time/observation.... If the little fellah is obviously suffering, I would find him a new home, or perhaps divide the tank to give him some space of his own to grow a bit.> Thank you again, -Katina <Wishing you well, -Sabrina> 

Molly Behaviour/Aggression - II - 11/06/2005 Hello again; sorry to keep bothering you guys but you give great advice. I wrote the other day about my three females not letting the male eat. I tried your advice but he died. <Sorry to hear this.> I think from the stress of the females harassing him. Especially one of my females. But the problem now is she's harassing the other two females. One of the females she has driven to the same corner where the male was. So should I remove her from the tank or get a new bigger male? <I would consider removing the "bully" - or perhaps increasing the number of mollies substantially.> My other male was a lot smaller than the females. There are only three mollies in a 29 gallon aquarium. I've had them there almost a month. I wanted to add three to four more. Would that slow her aggression?  <Quite possibly - but, of course, no guarantee.> I know mollies can be aggressive from reading your site. The thing is I don't want to get rid of any of them and I know they don't like to be alone. So if adding mollies isn't the answer should I just put her in a tank by herself? <That is certainly an option.... I would try adding more; a 29g tank can support more than 3 mollies, to be sure. If this fails, you can still remove the "bully" female.> Thank you very much. -Katrina <Wishing you well, -Sabrina>

Re: Quarrelling Mollies - Injuries & Infections (An Update) 11/1/05 The female molly died and the male seems to be less of a jerk now that he is the sole molly (he's kill all the others it seems). I went out & bought a test kit and here's what I've come up with: <ok> 10 gallon heated tank: Temp: usually around 80º Tankmates: 2 sunset fire platies and their fry: (1 larger fry, 1 itty-bitty fry), 2 golden AE's and the black molly male. Internal 10i filter, Submersible 5-15 heater (both enclosed in decorative "log") pH: 6.7 (too acidic, I know) <<Are the fishes showing poor health or other adverse reactions?  If not, don't mess about with the pH. MH>> Nitrite: .25ppm As for Nitrates I apparently didn't do the test correctly so the reading (40 ppm) is probably wrong. 1 gallon unheated tank: Temp: 72º Tank is currently empty pH: 7.0 (perfect) :D Ammonia: 1.0 (ewww)  <agreed> Nitrite: .25 ppm  <there should not be any sign of nitrite! this is very dangerous for fish.> Nitrate: 40ppm  <this reading is probably thrown off due to the traces of ammonia, nitrite> I went to Wal-Mart trying to find a good way to correct everything but there were a million different choices and methods. Can you recommend one? I need a "fixer" for just about everything: nitrite, ammonia, and pH. I'll probably pick up a Nitrate "fixer" too for when it gets out of whack.  <you need to do water changes....there is not a chemical that will correct your problems.. dilution is the solution my friend. just continue to monitor the water parameters, good luck, IanB> 

Molly Behaviour, pH and Alkalinity - 10/27/2005 Hi there. <Ahoy.> We have 4 Dalmatian mollies 3 female and 1 male. They are in a 55 gallon tank. We have had them for a week and a half now. The male has seemed to claim the heater as his. He will chase off the females if they get to close to it. <I have seen territorial behaviour in mollies before. Usually males are more aggressive with other males than with females, though.> The temp in there tank stays 80. The first 3 days or so the male bugged the females all the time. Now he doesn't seem to chase them to breed any more. He eats and will come away from the heater for a little. <Probably a good idea to keep a close eye on him, just in case.> One of the females which I think is pregnant was claiming that same corner yesterday and ran the others off. <Typical of a pregnant fish to chase others away from "her spot". I would still observe these fish very, very closely for a while, in case there is something pathogenic at play.> I just did all the test and here are the results nitrite is 0,nitrate 0,amonia .25 ppm., alkalinity 120 ppm., pH is below 7.0. <Better for this to be higher for mollies.> I am not sure how to keep the pH and the alkalinity balanced. I have pH Increaser should I use this? <Mm, instead, I would add a small amount of crushed coral or aragonite sand in a filter bag in your filter. This will help quite a bit. Start with just a little bit, though, and increase slowly over some days - test your pH regularly as you do this so you don't let it increase too much too quickly.> We have not done any water changes since we set it up. <Probably a good idea to start.> Thank you Katina <Wishing you well, -Sabrina>

Mollies Fighting?  Molly Death match! - 10/26/2005 I own a 10 gallon freshwater, heated aquarium. Tankmates include: 2 black mollies (the trouble makers) 2 sunset fire Platies (and one of their fry in his own "fry net") 2 golden algae eaters The black mollies are the only survivors of the original four. Lost one to what I think was bullying and another was fin rot (I think). Anyways, my smaller Molly has recently come down with a case of the "fuzzies", a whitish fuzzy patch (fungal infection?) <Or bacterial.... more likely bacterial.> around what looks like an injury on his side. The other molly, who is a bit bigger, often chases him around and butts his head into the injured molly's underside.  <Mm, sounds like courtship/spawning behaviour if the injured one's a female and the larger one is male....> The injured molly stopped coming to the surface to feed so I purchased a separate tank (1 gallon, unheated) for him to "recover". I put him in a bit of his old tank water in a Ziploc baggy for about an hour to let him get used to the new temperature then added him to his new little tank. Almost immediately a large rounded tube appeared from what I'm guessing is his anus. It was like a giant white poop and for awhile I worried it was his inner organs. But it eventually came apart like poop and is now on the bottom of the tank.  <That this was white is a little concerning, to me. Definitely keep this fish separate from the others for now.> The wound has lost quite a bit of its fuzziness (the fungal infection?) but he still won't come to the surface to feed and swims with his tailfin hanging down in a very pathetic-looking manner. Do you have any recommendations for treating the fungal infection (if that's what it really is) <Pristine water quality alone may affect a cure.... Test ammonia, nitrite, and nitrate; maintain ammonia and nitrite at ZERO, nitrite less than 20ppm, with water changes. If this does not help, you might consider a good broad-spectrum antibiotic.> and for what is causing my Mollies to attack each other like that? The bully Molly has a much larger dorsal fin and a smaller anal fin, tucked close to the body. The victim fish is much smaller overall has a more droopy anal fin <Would you say more "fan" shaped?> and a much tinier dorsal fin.  <This smaller fish may just be a female that the male thinks is cute. If that's the case, what you were seeing is actually courtship or spawning behaviour. It's usually recommended to keep three or four females per every male for this reason.> Thank you for all your help! -Jill <Wishing you well, -Sabrina>

Platy Killers  10/2/05 Dear Team, <Catherine today> I wonder if you can answer this, we have three Platies in our aquarium and they have just killed three of our other fish.  Can you give me any idea of why this may have happened.  <Not without a bit more information.  What kind of fish?  How big is the tank?  How old is the tank?  Why do you assume the platies killed the other fish?> Stephen F. Ellis  <Catherine>

One Molly, and More Comin'! - 08/08/2005 Hi, I have one pregnant molly in a 20 gallon tank.  I have no idea what to do.  I would greatly appreciate it if you could tell me what I need to do to keep my pregnant molly and her to be fry thriving. <Not much....  Maintain optimal water quality and be certain that the fry have plenty of places to hide from the hungry mother (best option is fine-leaved floating plants).  See here for more:  http://www.wetwebmedia.com/FWSubWebIndex/mollyreprofaqs.htm .> Thanks,  Tommy <Wishing you well,  -Sabrina>

Aggressive female balloon belly molly 7/23/05 Hi! I have 3 female balloon bellied mollies in an 8 gallon tank (1 orange,  1 spotted, and 1 white).  I bought them about two weeks ago and when I  first did I had a 4th one (a black female).  Unfortunately the black one  died the next day.  The orange one and the black one were always swimming  together and the white and spotted one hung out together and within that 24  hours there was not any aggression between the four of them.  Now  I notice that the orange one is ALWAYS harassing the white and spotted  one.  Is this because the white and spotted one hang out together and she feels alone? Or is she just aggressive because she is a little bit bigger than  the other two?  Thanks so much! You all have been most helpful! ~Laura <Likely more the latter... some individual mollies are just "mean"... but the size of the tank (the bigger the better) and sex ratios (two, three females per male) are important. Bob Fenner>

Mollies, using WWM 7/26/05 Ok I just sent you an email a few days ago about an aggressive female balloon belly molly.  The more I looked up things online I realized she is a he.  I am bringing these fish to college with me and do not want to have  to deal with fry in a tiny dorm room all the time.  I know they can still  have fry after 6 months of being impregnated so I am prepared for the next 6  months, I just did not want constant fry for years and years.  So I went  back to the pet store and traded him in for a female because I thought he would  be happier with males. <... uh, no> Well now that I have this new one the other two are  being really aggressive toward it.  Is it because she is new and they are  testing her out?   And if so, how long will they be aggressive toward her  before they accept her?  I just want happy fish that get along! Thanks so  much! Laura <Please read... on WWM re mollies... Bob Fenner>

Role Reversal Hi, I would like to ask why my female balloon molly chasing my male balloon molly. It is suppose to be vice versa right? I have 2 female and 1 male. Only one female chasing the male, but not the other female. Thanks <She may be ready to give birth. Or she may not think he would be a worthy father for some reason. Impossible to say for sure. She could just be mean. Don>

Molly is surface sucking First - great site - love it - it's kept me sane through getting my 10g aquarium set up and cycled... <Ah, good> We've got a mixed school of 5 - rasboras and black neons (survivors of an ick outbreak - they now school together) and one small pleco (we cycle them - when they get too big, a friend with koi ponds takes them) <Hope the pond stays warm throughout the year> We wanted to add an attractive, single fish - the fish guy at the pet shop suggested a molly and we loved the lyre-tailed black - so, we bought one...We think a female... <Okay> So far - the molly does well, is active, eats well, is not aggressive to the other fish, loves swimming through the bubble curtain at the back of the tank, and generally seems healthy. Our tank is heated (runs about 74 - 77 F), well aerated, very well filtered, and according to the test strips we use - it runs between 7.2 and 7.6 ph, about 120 ppm total alkalinity - we do have very hard water, but the tank cycles well - and the ammonia/nitrates/nitrites are at zero. We treat for chlorine and we do add salt (salinity is a little lower than you suggest for mollies - but they were not in that level at the pet shop, either...) <Not always necessary... if the water is sufficiently hard, alkaline...> My question - she has a habit that looks...well....odd - seen it in bettas, but...she swims to the surface and seems to "nibble" at the surface - just like a Betta gulping air or making a bubble nest. Is this normal behavior? <Actually, yes... take a look at the fish's mouth here... is modified for "surface skimming" for foodstuffs. Bob Fenner> 

Is she sleeping? Hello, I have a 10 gallon freshwater tank with 1 balloon molly, 1 marbled molly, one red wag platy, and about 10 fry that are 4 days old separated into a breeder net.  When I woke up this morning, my balloon molly was face down, tail up into the rocks just swaying there.  I took the net to see if she was just sleeping and she swam away.  But when I looked back 10 minutes later, she is just laying at the bottom.  Her fins aren't moving but her mouth is.  What is going on with her? Thank you so much! <<Hello. Please test your water, and let me know the results for: ammonia, nitrites, and nitrates. Thank you. -Gwen>>

Male Molly Behavior Hi - I have had two male mollies in an outdoor water garden that consists of a large faux terracotta pot (maybe 25 or 30 gallons), a spitter fountain, and several water plants in containers stacked on bricks.  I have had the Dalmatian molly for 16 months and an orange speckled "fancy" one for a few months. Last year, when it got below 70 degrees, I brought the whole water garden into the garage and put an aquarium heater in the pot.  The Dalmatian did fine and was back out in the yard again this summer.  His companion made it through the winter in the garage but died within a couple weeks of being brought outside this spring.  So after mistakenly buying a pregnant female and having babies (gave them to a good home), I finally got the orange male that I have now. I guess I am embarrassed to say that I never monitored the water.  I would clean out the pot every few weeks with a complete water change and had snails to keep the algae down.  Here in Dallas, the sun would evaporate quite a lot, so I would add about a gallon of water a day.  In the winter, I never changed the water - just added water to keep up with the splashing from the spitter fountain. Once again it is time to bring them in for the winter.  However, this time I thought I would splurge and get them a real tank and set them up in the kitchen.  I got a so-called complete, 5 gallon hexagonal tank with a pump and biofilter system included.  It's been a couple days now and the orange one is running the Dalmatian ragged.  He is constantly harassing him by nosing at his anal fin area.  In the water garden, there were places for the fish to hide (usually in the brick holes) so I never really noticed harassment.  Now that they are in closer quarters, there is nowhere to hide. Is 5 gallons too small for two male mollies?  Is this harassment temporary while they adjust to new surroundings?  Should I get something for the Dalmatian to hide in?  Maybe I should just put them back in the water garden in the garage for the winter. Sorry to ramble so long and be so ignorant, but I'm really a gardener that thought having fish would be a neat addition to my water garden.  I was going to get goldfish but the pet store said that it would be too hot for them in the container and suggested tropical fish.  I never thought that I would actually have fish that lived this long (or have babies).  The mollies really have been trouble free and apparently quite tolerant of my ignorance about how to properly care for them, especially when I read about all those nasty diseases on your forum.  I guess I have some beginner's luck, but don't want to press my luck. Thanks in advance for your guidance. < Male mollies are very competitive for territories because they want to attract females and chase other males away. Try some floating plants and lower the water temp to the mid 70's. The lower water temp may reduce their metabolism and thus the mollies desire to spawn. If that doesn't work then a larger tank may be needed.-Chuck> FlowerFreak

Aggressive male molly question Hello.  I really enjoy reading your site and I've learned a lot from it, thanks for all the info.  I was hoping you might be able to help me with a small problem I'm having concerning my mollies: A few days ago I purchased 3 mollies (one male black molly, and two orangish colored females) to add to my tank in hopes of giving the female black molly that I have had for about 2 years some company.  More specifically, I was hoping that putting more of her own kind in there would keep her happier, or at least distract her, and tone down her aggressiveness with the glassfish and longfin danio she shares the tank with. I guess it worked in a sense, only  because now she's too busy being chased by the male molly to bother any of the other fish.  I knew that male mollies could harass females to the point of death if the male female ratio wasn't correct, which is why I got the two females also when I got him.  <Good plan... do you have enough decor... plastic or live plants et al. for the fish to get away from each other?> The people at the store thought that the male should be equally interested in any females no matter what color they were, and I agreed.  But so far, he only chases the black female and completely ignores the other two.  So is the problem indeed that he is only interested, or at least more interested in the female that is the same color as he is?  <And perhaps the same species... there are different species of mollies.> The only other thought I had was that perhaps the two orangish colored mollies could possibly really be platies.  <Interesting possibility> From pictures I can find and what I've casually observed at stores, they look quite similar in body shape (and their tanks were next to each other in the store).  Is there some physical trait that they differ in that I could look for to be sure I have mollies and not platies? <Take a look on WWM and fishbase.org and through Google for pix of both... mollies are rounder in cross-section, and have mouths that are more upturned...> I'm not sure what to do, my first thought was that I need to go buy another female black molly to keep him occupied and give the current female a break, but my tank is only 10 gal. and I probably shouldn't even have as many fish in there as I do now.  <You are wise here> She has started hiding constantly (which she had never done previously, not to mention she has displaced the poor longfin danio from his usual longtime hiding spot) and I can see spots where it looks like the male has been biting her.  I am rather attached to her, as I have had her since she was a fry (and especially since none of her siblings survived) and I would hate to see her end up dying because I put more mollies in thinking it would make her happier.  Could there be some other reason that he's only interested in her and not the other two? It couldn't be that she's somehow giving off signs that she's 'more receptive', right? <Mmm, not necessarily> As far as I know, I've never heard of anything like estrus in fish, and I guess that doesn't seem likely anyway. Other than separating him (which will be difficult because I can't afford another tank, even more so in terms of space than cost wise), I don't know what else to do.  Any answers, help or suggestions would be greatly appreciated.   Thank you so much in advance,  Lea <Lea, if it were my tank, I'd trade that male back in... ASAP. Bob Fenner>

Odd molly behavior in a small tank <Ananda the molly nut ... or is that molly bolt? ... here today...> I have a 5 gallon aquarium with a platy and two guppies. I recently added a black & white molly. <You are going to need a bigger tank Real Soon Now.> (I know they interact well with platy's, and the assistant at the pet store assured me he would be fine with the guppies.) <Should be fine.> Nonetheless, I was very cautious in adjusting the molly to its new environment. For the first few days, everything seemed fine. However, he has started swimming incessantly in circles, <He needs more space to swim.> while the other fish seem to "hide" in the corner. <I think I'd hide, too; the molly is the most aggressive fish of your bunch.> This seems to be a bit active for a molly. I change the water frequently, checking temperature & pH levels & all that stuff. <Good to hear!> The only things I could think of that might cause a difference in behavior would be tank-size to fish ratio. I think 4 fish in a 5-gallon tank may be pushing it. <More than pushing it in this case. Due to the size of the fish, your tank is now overstocked.> The other is that the molly appears to be slow in adjusting eating habits. I've fed the others routinely for months, once at 8 am and once at 8 pm. <Sounds good.> The molly just doesn't seem to have caught on yet, he's the last one to start eating, <Weird. But, as you say, could be an adjustment issue. Or it could be because he feels crowded.> and often eats off the bottom. <Normal.> I'm sure that though he is my biggest fish, he is not consuming as much as the others. <Hmmm. You should be feeding them a flake with a decent amount of Spirulina; mollies are plant-eaters by nature. Mine will eat just about anything I give them, but I think the OSI Spirulina flake is their favorite. They like to nibble at sinking algae tabs, too.> Any other suggestion you could make would be greatly appreciated. <Get a bigger tank and a good power filter if you don't already have one. Keep your current tank for quarantine/hospital purposes. And enjoy your new fish!> Thanks, Stephanie McLeod <You're very welcome. --Ananda>

Mollies acting odd! Hi, just got a 29 gal kit March 7th, and currently have 12 mollies (Gold Dust and Marble), and 3 young Albino Corydoras.  I'm having water quality problems.  I think my ammonia test isn't working (it's the water tube test, not the strips) because when I use it, I show NO ammonia, but when I have my water samples tested at Petco (they use the strips), then they show ammonia! <Very possible, this happens once in a while. It sounds as if you may be overfeeding the fish. After this amount of time your biological filter should be established and the ammonia and nitrites should stay at 0. Cut back on the amount and/or frequency of your feedings and it should help.> I also was having a nitrite spike and had high pH, which Petco people told me to bring down.  So, I've been doing water changes over the last few days and have finally brought my nitrites down to 1.0ppm (they were at 5.0ppm).   <Ouch! Even 1.0 is still quite high and it's a wonder any of the fish are still alive after 5.0!> I also treated each bucket of new water with Stress Coat, Water Conditioner, and pH balancer (my tap water was off the charts when I tested it...must be 8.0+).   <Just make sure that the water in the tank stays at the lowered pH, sometimes it will spike back up.> MY PROBLEM IS...my mollies are acting weird, MANY are hanging around the surface moving their mouths a lot, they're not moving and swimming around like usual, and some will swim in place, others will sit on the bottom and move only every now and then. <Sounds like they are uncomfortable with the ammonia and nitrites. These are common symptoms of poor water.> Some still swim around, but only a few. I noticed 1 molly jump around on a rock, rubbing his body on it a few times. <This could be the beginnings of ick or just a reaction to the ammonia and nitrites.> I found 1 molly dead this morning, checked his gills and they're nice and pink, no parasites, or weird markings on him.   <Probably a reaction to the nitrites then.> My Corys act fine.  And there is about 3 tsp.s of aquarium salt in the tank.  My nitrites are at 1.0ppm, nitrates 0ppm, ammonia=??? (need a new test kit, I'm still showing no amm.), but my pH is 6.8 which is a drop from 7.0 an hour ago!!!!  Is this the problem?   <pH will fluctuate a little throughout the day so I wouldn't be concerned about this.> Have I over treated my water in trying to decrease the danger to my fish?  I don't know what to do, they are clearly stressed!  They still eat, but I don't know how to help them.  I don't want to damage my biological filter by doing ANOTHER water change, but should I? <For now, just keep up with the water changes and bring the ammonia and nitrites down to a consistent 0. I don't think you over-treated the new water although you could probably get by without adding the Stress Coat. Small water changes aren't going to damage your bio filter, they're actually going to help it.> And should I use something to INCREASE my pH now that it is falling?   <Nope, they are adapted to the lower pH now and raising it would cause more problems.> Aren't mollies supposed to be in water with a higher pH?   <Yes, a little higher than what yours is. They do best in a pH of 7.5 to 8.2. You can bring this up by not treating your newly added water with as much of the pH reducer but the pH level needs to be brought up slowly or it can cause even more problems.> What am I doing wrong?--fish_puppy <Do some reading at http://www.wetwebmedia.com and at http://www.fishbase.org to find out more about your fish but I really think the main problem is overfeeding. Ronni>

Aggressive Mollie Hi, great website you have here! <Thank you, we hope that you find it informative (not to mention fun).> I have a black molly, female, who is so aggressive. I have a 46 gal. tank, everything has been going good. My chemical levels are all perfect. I also have one Silver Dollar, one Australian Rainbowfish, one Guppy male, two Guppy females, one male Swordtail, and three female Swordtails. I know my stock choice isn't so great, that was a mistake of mine. I'm new to this hobby and I've learned that I definitely need more than just one fish of all my breeds. So I'm working on adding stock. <It's good that you have learned that, researching your fish and knowing what they need to be happy definitely increases the fun you have with your fish.  Just be careful not to over stock your tank.  If you will be adding more fish, you might want to think about increasing the filtration on your tank.> In the meantime though I'm really worried about the aggressiveness of my molly. I got all my fish as babies, and the molly is about two inches now. She's really growing and the bigger she gets the meaner she gets. <That is a Mollie trait, I've never been a big fan of these fish because of that reason.  I find them to be aggressive in nature, they pester many tankmates.> And mostly it's just with my Swordtails and particularly my male Swordtail. I thought it was very odd that she seems to just pick the Swordtails to pick on. <Perhaps your "she" is a "he".  Male of the species will pick on other males for breeding rights.  The Mollie thinks that your male swordtail is a competitor and is trying to chase the other one to breed with the females.> I thought these two breeds did well together. <Yes they do.  Though it has never happened in my tank, I have been told of them cross breeding.> She is constantly chasing them. When I recently (about 3 weeks ago) added two of my female Swordtails it didn't take long before I noticed a nipped fin in one of them. Since then her fin has healed. I haven't noticed any more nipped fins except for in my male Swordtail. My molly has taken a bite out of his top fin and quite a chunk off the end of his sword. I will be moving her to a tank by herself for the time being since noticing that today. <Separating her is the best choice you can do now.  She will not stop the harassment, and it will only get worse as the fish ages.> Why does she harass him so? She chases him constantly, when of course she's not chasing the other Swordtails. <In my opinion, I think the molly is chasing the swordtails for breeding issues.> Is she mad because she doesn't have any other mollies to hang out with? What should I do with her? I hate to give her up, but I don't want her harassing anyone else I have or may get. <My opinion you should probably trade her in for something else.  She will not stop this behavior, and adding more will most likely add more headache to the problem.  I suggest you take her back to your LFS and see if you can find a Rainbow or Silver dollar to add to the tank.  At least then you know that you will be adding a fish that will be okay in the tank.  Plus it will be good to add more of the same fish to enlarge the schools.> The water conditions are favorable for her, 8.0 pH and alkaline and a little salt. So I didn't think that the water conditions were causing her aggressiveness. Thanks for all your help you can offer me. Stacie <That is the headache with Mollies, in my opinion they are very annoying fish.  My suggestion is to remove her from the tank, either give her a tank all to herself (with other mollies if you wish).  Or you can return it to the pet store and try to get a mate for one of your other fish.  Good luck -Magnus>

Aggressive Molly Hi.  I hope you can help me.  I started with 3 black mollies- 2F, 1M. After about 1 week, the male began chasing and biting at the females during feeding times (only during feeding).  1F ended up dying.  I've never had this problem, past mollies have always been so peaceful.  He doesn't chase anyone else in the tank.  Any info on if this is normal?  Tank is FW 65 Gallon, nearing the end of cycling.  Thank you, Kelley. <<Kelley, sounds normal to me. Mollies can be quite aggressive, which is why we usually advise people to keep one male molly per three to four females. Remove the obviously impregnated females to a safe breeding trap, so she can have her babies in peace. Stressed females can and do, die, due to males constant harassment. Make sure your water quality is always good, keep nitrates low, and make sure the temp is always stable, 80F is fine. Add some more females, things should get better, but keep in mind that mollies are not peaceful fish. They just vary depending on their own character, some are worse than others. They are also herbivores, so try feeding them twice a day, it may help. -Gwen>>  

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