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FAQs on the Rainbowfishes 2

Related Articles: Rainbowfishes Fishes at the rainbow's end;  An introduction to the Atheriniformes, the rainbowfish and silversides by Neale Monks

Related FAQs:  Rainbowfishes 1, & FAQs on: Rainbow Identification, Rainbow Behavior, Rainbow Compatibility, Rainbow Selection, Rainbow Systems, Rainbow Feeding, Rainbow Disease, Rainbow Reproduction,


What would you do? Stocking 20 gal. 9/9/08
Hello Crew!
<Hello Audrey,>
I am in need of some guidance. We have recently upgraded our tank to a 20gal. We moved the plants and snails to the new tank. After a while, we decided to get some Pseudomugil Furcatus. We brought home 6 of them. All was well for the first 36 hours or so.
<Lovely little fish; hitherto very rare in the trade, but thankfully starting to appear a little more often.>
After about 36 hours I found fuzz on one of the males - not ick, one big infection spot. The fish was still active and eating at that point so I moved him to a treatment tank and treated with what I had around (Furan - supposed to treat mouth fungus, cotton wool and infections so I thought it would work). I found him dead the next day. I examined the body and saw a big red zone, an injury under the fuzz, so I think he died as a result of a mechanical injury, either in transit or at the store (they're too small and fast to do a thorough exam at the store).
<I'd be treating with a combination Finrot/Fungus medication such as eSHa 2000 or Maracyn. This should handle the "big three" -- Fungus, Finrot, and Mouth Fungus -- all of which are possibilities here.>
The day I found the injured male dead, I also found a dead female in the main tank, this one with no visible sign of illness or injury.
<Do check other issues: water chemistry, oxygen, temperature. It is possible they simply travelled badly, but still, for the sake of your peace of mind, check the tank.>
Now I am left with only four fish. I think they would be much happier in a bigger group. I'm also worried because I have a trio and a solo, and, although the lone female comes out for food, I have a feeling she'd be more happy if the dominant fish had more fish to chase away.
It has barely been a week and, while the other 4 fish seem happy, I'm worried they'll die suddenly like my female.
<Always a concern when you're keeping an apparently delicate species for the first time.>
Now, this is my dilemma. This LFS where we bought or fish is the best close to us, they're the only serious, specialized fish store around, but we haven't been happy with the fish we've bought there so far. There is a pet store that has healthy-looking, vigorous fish, but their selection is limited, and they don't have any Furcatus. There is also a very new fish store a little further away who insists heavily on the virtues of wild-caught fish - I'm weary of them because the seller told me I was crazy to have a heater for my Betta (another tank), and was rambling on some nonsense about UV sterilization. I know this doesn't mean they have bad stock, but I don't know if I can trust their husbandry. I also don't know if they have Furcatus in stock.
<You pays your money and you takes your choice... In this case, I think you need to focus on the matter at hand, grabbing a few more female Blue Eyes. Get them from whichever store has them, or online if you prefer.>
So, do I wait a few weeks before I get new fish until I'm certain enough my current 4 are going to make it? But if I do that, should I worry about my lone female?
<Depends on the price. If getting another batch only sets you back a few dollars, then go for it. I'd be looking to see that my existing stock are settled in and feeding. I'd like them to have nice rounded bellies -- and just for once, I'd perhaps overfeed slightly with live daphnia or whatever just to be sure. If this was all in the positive, I'd order/buy some more Blue Eyes.>
If I do get more fish should I go back to our usual LFS and risk buying another half-dozen, and hope those make it?
<Ask if he can get a batch in just for you, and you pick them up when they arrive before they're unboxed. Otherwise, buy a decent size group, factoring in a certain amount of attrition. Maybe get twice as many females as males, just to be on the safe side.>
My other choice is mixing the Furcatus with long-fin rainbows (those are easy to find) - would they even interact, given they're not the same species?
<Not even the same family, so doubt they'd have any meaningful interaction.>
What would you do?
As usual, I appreciate your guidance. I have options, I just don't know where I should go from here...
Thank you,
<Good luck, Neale.>

Re: What would you do? Stocking 20 gal.  9/10/08
Hello again,
I'm including the previous correspondence below for reference.
Well, things didn't work out. I lost another male a day after I wrote you, then yesterday night one of my remaining females pineconed (I euthanized her when she started swirling). I have two Furcatus left. I'm wondering if I should put my misfortunes down to bad stock or bad husbandry.
<Maybe both...?>
My tank is 20 gal standard, with Fluorite substrate, plants (Bacopa, Anubias, Amazon chain sword, Dwarf Hygrophila), two Coralife T5 bulbs. pH is steady around 7.4-7.5. Temperature was a bit high, hovered around 80 but is now going down with the cooler weather coming in, is now steady around 78 - this is with the heater set on low, if I remove it, it goes down to 70-72.
<In summer I have to confess I tend to switch the heaters off; leaving tanks to daily fluctuate slowly from 68-78 F is entirely in keeping with the wild, and nothing most tropical fish can't handle. Overheating, and the resulting loss of oxygen from the water, is more critical.>
No detectable ammonia, nitrite or nitrate (the algae must use it all). Filtered with two Aqua-Clear Minis (each rated up to 20 gallons), with sponge. One with added ceramic media, the other with carbon (I know what you think of carbon - I'll explain myself later). We were good in the last few weeks and did weekly water changes, about 25% each time. Not much vacuuming because the plants were new and there were only three snails in the tank. We had a problem with BGA these last few months, but with the new substrate, new plants and new lights it's slowing down radically. We still remove it manually.
<Very good.>
The first thing we tried keeping was Mollies, but they all died of Camallanus over the course of a few months. They were in brackish water too. We now know the tank was too small anyway.
<Ah, yes, Mollies can be sensitive. Camallanus is not common among the (Asian) fish I see in the UK; it seems to be more of a problem with (perhaps) the Mollies bred in Florida?>
The Amano shrimp lasted a long while (several months), and we used to have Cherries also. At some point, they started dying too. The only thing I changed was that I stopped using carbon, so I put it back. No luck. Our new batch of Cherries didn't make it past two weeks either. The Apple snail seemed to fare better, he's been with us for about 6 weeks and seems happy.
The Nerites, though, are with us since the beginning and growing at a steady rate. The beginning was when we got our Betta, over a year and a half ago. He's his usual increasingly-grumpy old self, in another filtered, heated tank of his own.
<Interesting; Nerites are quite good "bellwethers" and will climb out of the tank if oxygen drops or they get too warm. So if they're happy, the tank can't be seriously hostile.>
Basically, even if we know that Bettas are resilient, I'd be surprised we kept it this long (even neglected it at some point along the way) if our husbandry or water was this bad. And snails are sensitive to contaminants, or so I hear, but they seem to be doing fine. But we seem to be serial shrimp and fish killers.
<Well, shrimps are sensitive to copper. Snails are to a varying degree, but shrimps usually react immediately and fatally. But as you say, this mix of fatalities and survivors is interesting.>
What is our problem? Did we start with bad stock?
<Always possible. Fish are often bred to a price rather than a standard, and couple that with ropey husbandry in some stores, and the track record of many species is poor. None of the fish you're keeping is "delicate" by default, so poor stock is certainly something I'd consider.>
Or are we doing something wrong?
<Difficult to say; if you're doing things by the numbers, keeping on top of water quality and feeding issues especially, I can't imagine you're doing anything fatally wrong.>
Can you point us in the right direction?
<The first thing would be to leave the tank as it is for a couple weeks. Don't do water changes. Every 2-3 days, do nitrite and pH tests. Keep a record. Ditto water temperature. Try and develop a picture of how the aquarium is operating in terms of environment and stability. By the end of two weeks you can return to your normal maintenance schedule. Slight variation in pH over time is normal, but if it's great (e.g., from 7.0 to 6.0) then you may have a problem there. Carbonate hardness is often overlooked in this regard.>
What would be your absolutely easiest, sturdiest, non-plant-eating, compatible with inverts, non-aggressive, easily available fish for a 20 gal tank?
<Many options. Depends what you're after. At the moment in my 10-gallon tanks with shrimps and snails I have peacock gobies, Aspidoras pauciradiatus catfish, bumblebee gobies, and Limia nigrofasciata. Wrestling halfbeaks are also good, being able to adapt to a very wide range of water chemistry values.
Most of the smaller tetras should be good too, though they usually prefer soft water. If you have hard water, then the smaller livebearers are better choices. Endler Guppies for example should be easy to obtain and tend to be quite robust. Don't overlook "feeder Guppies"; these are much hardier than fancy Guppies and have added benefit of more natural colours.>
I doubt we'll have the heart to try Furcatus again any time soon.
We're at the point where we barely glance at the aquarium anymore because we always expect to see some tragic event taking place. This is supposed to be a fun hobby...
<It IS fun... but sometimes it seems otherwise. Once a tank is stable and working, and provided you haven't added too many fish or the wrong type of fish, they're pretty much autopilot things that need little maintenance. Do be patient, and go slowly, leaving things to settle for a while before rushing out to buy some more livestock.>
Thank you for your guidance,
<Good luck, Neale.>

Rainbow fish  5/10/08 hey, I am starting a rainbow fish tank, <Er... I guess you didn't read the 'house rules' regarding grammar, punctuation, etc. http://www.wetwebmedia.com/faqstips.htm Also, here in England at least, someone saying "Hey" to a complete stranger is considered extremely rude.> what are some recommendations (plz no tank sizes) <Why don't you want to know the tank sizes? All the fish you're considering need a fairly spacious tank, certainly upwards of 180 litres/45 gallons. Non-dwarf Rainbowfish comfortably reach 10-12 cm in many cases, often slightly more. It's just plain cruel to keep them in any aquarium less than 1 m/36" long -- they need the swimming space.> I am putting 4 Australian rbs, 4 incisus rbs, 4 boesmani rbs, <You need at least 6 of each of these. Not 4. These are *schooling* fish, and you will NOT see them at their best in small groups. They need to be in big groups so that the males and females are in sensible, equal numbers. ONLY kept this way will the group be peaceful and the males develop their strongest colours. For example, some people try to keep just males, and then wonder why their Rainbowfish don't ever become fully coloured. Well guess what -- those colours are for a reason -- to show off to females. No females, no mating colours. And if you want a nice mix of males and females, you need 6 of each species, at least. In addition, in groups of less than 6 the fish won't school. So instead of nice, coordinated group of fish schooling together, you'll get a jumble of scared-looking fish with weak colours. Trust me on this: after a couple of weeks of this, you'll be very disappointed with your aquarium. So instead of three different species, how about 12 specimens of just one species. The result will look a hundred times better, and this is how professional aquarium designers work when creating exhibits with Rainbowfish for offices, public aquaria, etc.> like what tank ornaments/substrate etc. <Rainbowfish do indeed like tank ornaments and substrate.> Thanx <Chz Neale>

New Tank question, stkg. Melanotaeniids, Colisa lalia   3/12/08 Hello. I am new to aquariums and have purchased several books and read tons on your site (which has been VERY helpful) in an attempt to be the best fish owner possible. I have some questions that I can't seem to find specific answers to, even though I have done several searches on your site. Some background info: I purchased my fish from a local fish store that has the best reputation in the area. These are the fish (all locally raised) I purchased based on their advice: 3 angels (started with 4, one just died after a bout with an eye infection fish store thinks was due to injury - I removed sharp fake rocks) <Bad choice for your first aquarium, and for what it's worth, the eye infection is more likely aggression between the Angels followed by a secondary infection. Fish just don't normally scratch themselves.> 3 turquoise Gourami (again started with 4 but one died almost instantly, fish store said sometimes that "just happens"!??) <Fish Store somewhat correct. These are Colisa lalia, a fish that is plagued with an incurable viral disease. Inbred forms like the turquoise variety are even more flimsy than otherwise. Colisa lalia is a complete waste of money.> 2 blue rainbow <Should be kept in groups of at least six specimens: Melanotaenia spp. are schooling fish, so what you're doing is cruel. Depending on precisely what species you have, these may be too large for your tank. Many Melanotaenia reach 12-15 cm.> 2 Hoplo catfish (acquired about 3 months after the others) <Far too large for your aquarium; Hoplosternum littorale gets to over 15 cm in length and is extremely boisterous in temperament. A superb choice for a 55 gallon tank; an appalling one for anything smaller.> I have a 29 gallon tank that I set up and let run for 2 weeks before purchasing any fish. <Just "running" isn't enough -- how did you mature the filter? What source of ammonia did you add? Ammonia from a bottle? Bits of rotting shellfish? If you did nothing, and just let it sit there, then it is no more cycled after two weeks than it was when you started.> All the fish did fine in their new home (excepting the one Gourami). I test my water regularly and do a 20-30% water change every week. I have had the tank set up for almost 6 months so now I am in the process of adding live plants. (I put in 2 live plants a couple of weeks ago and they did well so I just added some more). So now on to the question(s): What is the best temperature for this grouping of fish? The fish store said 72F but everything I read says it should be warmer. Should I listen to local advise or let majority rule? <Neither. Science isn't democratic or based on local wisdom. Each fish has its own preferences dependent on its point of origin. Buy and read a decent aquarium book so you don't have to depend on what the guy in the shop says. Aiming for 25 C/77F would be about right for your fish.> I have been having a heck of a time keeping the water quality stable. It seems I am always fighting against high ammonia or high nitrites/nitrates. Since I monitor this regularly, I am able to take corrective action before I get any further than the "mildly stressful" levels according to the test kits - but I would REALLY like to get everything stable and not always be worrying about what is going wrong!! <Poor water quality depends on three factors: stocking, food, and filtration. If you are getting poor water quality even six months after setting the tank up, then you are either overstocked, overfeeding, and/or under-filtering. Pick and choose from these. Do also check you aren't doing anything stupid like killing the filter bacteria every time you open the filter, for example by changing all the media or running the media under a hot tap.> I have hard water with a pH of 6.8 and currently my ammonia and nitrite readings are 0. <Fine.> I think maybe I am feeding too much? I read that as long as all the food is eaten in a couple of minutes, then it is the correct amount. <Depends on the fish and the food. A juvenile Angelfish for example needs 3-4 "flakes" per day. Consider each flake about the same a medium-sized steak would be to a human. Alternately, a single wet-frozen cube of bloodworms would be adequate for all your fish for one day. Fish need very small amounts of food.> My fish do eat all the food in that time period and come to the top afterward acting like they are starving, so could it be I am still feeding too much? <Maybe.> How do you know exactly how much to feed? This question has been driving me crazy for six months! I alternate between flake food and frozen brine shrimp, and I just started giving seaweed 1-2 times a week. I don't want to overfeed but I also don't want my fish to be hungry! <Well-fed fish should have a gently rounded abdomen. If the abdomen looks chunky or swollen, you're overfeeding; if the ventral surface is concave or "knife-edge" in appearance, you're underfeeding.> Then I just got a new filter. The one I had was an used AquaClear 70 that worked OK but made a horrible racket and I just couldn't take the noise any more! So I purchased a Marineland Emperor 400 (for up to 80 gallon tank) as I liked the idea of the bio-wheels and not risking the biological filtration every time I cleaned the filter. I know this is big for my tank but I went with the assumption that it would keep the water cleaner (and maybe therefore help stabilize everything) and also I hope to get a bigger tank in the future and this way I won't have to buy another new filter. I added the filter material from the old filter to start with (planning to remove it in a couple of weeks) in an attempt to keep the biological filtration going - I have no idea if this worked. <Should do, but don't remove the old filter media for at least 6 weeks.> But this filter makes the water much more active and I don't know if my fish like it! My Gouramis are turning darker since the change, even though they are eating and swimming normally. Is this grouping of fish OK with active water or should I change back to a smaller filter that won't move the water so much? They are all swimming around fine, not seeming to be buffeted or anything, but I notice it especially when feeding as the flakes now move rapidly around the tank and the fish get pretty hyper chasing the food. Is this stressful? My rainbows are chasing each other at feeding time and they never used to do that. <What matters is water turnover. Look at your filter: it will have a turnover rating in gallons (or litres) per hour. Compare this to your tank. You are after 4-6 times the volume of the tank in turnover per hour.> I raised the water temperature to 77F when I was dealing with the hurt angel (per fish store) and I haven't lowered it yet. Could that be the reason for the hyper behavior and color changes? <No idea, but leave the temperature there anyway.> Overall my fish seem happy with each other and the new plants (nibbling on them and hiding in them), but the angels are starting to get really big and I know the rainbows and Hoplo can get big too so I am worried about whether they will continue to get along. Or if maybe the angels are harassing the Gouramis and that is the reason for them getting darker colored? <Possible, and the Hoplosternum are also a bit more robust that one would normally want with Gouramis.> I also notice a white area on 2 of the Gouramis (it is not raised or cottony or anything, looks more like a small layer of scales is gone) which makes me wonder if there is some fighting going on of which I am not aware. <Or the start of Dwarf Gourami Iridovirus.> I want to be a good fish owner and I love my fish, but so far I have spent much more time worrying than enjoying! How do I create a happy, stable aquarium environment? <Primarily by reading first. Knowledge is power.> I apologize for the long message. Thanks so much for your help and all the invaluable information on your website! Cathy <Good luck, Neale.>

Re: New Tank question... Outside power filter   3/14/08 Thank you for your response to my questions. Your response has raised two more questions. I did search your site before writing to you again, and I spent almost 3 hours reading without finding the answers to my questions, so I hope it's OK to write to you again. <It's fine! Ask away!> The first is concerning the fish I was advised to purchase. I am stuck with these fish now and want to make the best of the situation. <Agreed.> I feel really bad about the rainbows and plan to get a larger tank and more rainbows as soon as it is possible. So that leads to my question - I have already had these fish for 6 months and am not sure how long it will take me to gather the money for the larger tank set-up - at that point, I can only assume that the rainbow fish I have are going to be a good bit larger than the new fish. Is this going to be a problem in terms of them getting along and schooling, etc.? <Shouldn't be a problem. Rainbowfish usually school with one another happily regardless of size. Mature males might chase one another, but normally no harm is done.> I'm also very aggravated that they told me to get the hoplos as I told them I wanted two small catfish... and they were small when I got them :-) but have grown an enormous amount already and are very, very active - running into/over all the other fish if they happen to be in their way <Indeed, Hoplosternum littorale is far from a "small" catfish.> The 2nd question regards my new filter... it turns over 400 gallons per hours. I have a 29 gallon tank so this is obviously more than 4 to 6 times the volume of the tank. Does that mean I am now over-filtering? <Seriously? 400 gallons per hour is a HUGE filter. This would be a top-of-the-line filter costing several hundred dollars and would be churning a 29 gallon tank into something like Niagara Falls! I'm pretty sure you're misreading something, and what you have is a 400 litres per hour filter, which is pretty standard for an entry-level filter. 400 litres is about 100 US gallons, or in other words a turnover about 3 and a bit times the volume of your tank per hour. Under-filtering rather than over-filtering.> Do I need to get rid of this filter and get something smaller? I am reluctant to do that (since I am planning to get a bigger tank), but I will if it is what is best for the fish. <Save up for the aquarium. At this point your problem is you have a bunch of fish that need a bit more space than you have. I'd recommend at least 55 US gallons. To keep costs down, save up for that tank and then install an undergravel filter. Coupled with the filter you already have, these two different filters will combine to provide excellent water quality. Undergravel filters aren't compatible with plants that have roots, but they're fine with floating plants and plants stuck to rocks (like Anubias and Java fern). Old school technology perhaps, but cheap and effective.> Thanks again for your help! Cathy <Cheers, Neale.>

Re: New Tank question... filter According to the box, my filter does run 400 gallons per hour (see specs below)! It is a huge filter - taking up most of the back of the tank. I paid around $80.00 for it. The water is active but not churning... should I get something smaller? Or maybe just figure out how to adjust the flow pump (that wasn't in the directions)? Thanks! Cathy Marineland - Emperor 400 Power Filters *Model Number **400* *Flow Rate (L/H) * 1500 *Aquarium Size (L) *<300 *Flow Rate (GPH) * 400 *Aquarium Size (G) * <80 <Hi Cathy. Okely dokely; my mistake. But seriously, a 400 gallon per hour filter on a 29 gallon tank will have a turnover of more than 13 times per hour. That's more than the average marine aquarium! I can't imagine angelfish and other community fish of that sort being happy. The normal turnover for community tanks with freshwater fish is between 4-6 times per hour. In other words, just as the ratings suggest, this filter would be ideal for an 80 gallon tank (5 x 80 = 400). So yes, I'd be looking for a smaller filter, and would save this one for as/when you get a large tank. Cheers, Neale.>

An addendum: Regarding Emperor 400 filter On 3/14/08 Neale answered a question from Cathy (Re: New Tank question)   3/15/08 Hi there, Crew! I just had a note to add. Regarding Emperor 400 filter On 3/14/08 Neale answered a question from Cathy (Re: New Tank question) regarding her Emperor 400 filter on her 29 gallon tank. Neale suspected that this filter couldn't possibly be so vigorous as 400 gph, but this is actually what it is rated at! In fact, I've seen two of these filters powering a 250 gallon tank with a single Koi, at my fave Pan Asian restaurant. It seems to suffice. This web page explains some basic modifications you can make to maximize efficiency: http://www.cichlid-forum.com/articles/power_filter_tricks_v.php Emperor filters are workhorses, and they do deliver ample flow. Unfortunately, these filters are the "cartridge type" with some blue floss and crumbles of carbon in a grid...I *highly* recommend to anyone who uses them, that they swap out the disposable cartridges for the largest AquaClear media they can find. Specifically the foam sponges and the Biomax bags. All of my tanks have hang-on back filters (some also employ canister filtration) and I use AquaClear media on all of the hang-on back filters, even though some of them are not AquaClears. The AquaClear media comes in an array of sizes, so will fit most any HOB filter. Rinseable, reusable media is the way to go! Incidentally, that filter must be roiling the water on that 29 gallon tank a whole lot. Since as I recall, Cathy has three dwarf Gouramis in there, maybe she should try to diffuse that flow a bit. One suggestion would be to secure floating plastic plants just under the filter's flow path. Some black binder clips holding up the plants on either side of the filter ought to do the trick, although a more elegant and lasting solution could probably be effected eventually. Just food for thought! As always, thank you for all your efforts. Nicole <Thanks much for this Nicole. Will send along to NealeM and accumulate. Bob Fenner> <As Bob said, thanks for this. Without the filter being named in the original e-mail, I simply had a hard time imagining anyone would put such a big filter on such a small tank. But I was wrong! I agree with you, the water current is perhaps overkill for Gouramis, but then again, I imagine the "gallons per hour" of the average Southeast Asian river is pretty substantial, too! Cheers, Neale.>

Neale re: threadfins (Rainbows)    4/24/08 Hello again Neale, <Hello Aileen,> I have been fish keeping almost a year now and it amazes me how much I learn every time I look through pages of this site. Sometimes too much and the information gets all jumbled in my head (could be age too) and other times I learn enough to lead me to ask more questions.. it really is a wonder resource. <Thank you!> You mentioned some time ago that if I wanted threadfins I should consider another tank. I thought you were nuts at the time but...I am going to look at a used 40g tomorrow. Actually somebody had a 100g I can have but I think two monster tanks might be a bit much. My thinking is leading me to include in this tank: threadfin rainbows, wrestling halfbeaks, Corydoras and then I was wondering about bumblebee gobies or something with some colour. I was reading on WWM that most bumblebee gobies are considered brackish except one species, which may or may not, tolerate fresh water better? <BBGs are complicated: you cannot possibly identify species; even scientists have trouble doing this under a microscope, let alone with live fish! Most BBG species seem to be found in a variety of habitats, from blackwater streams to brackish water. But in aquaria they are temperamental, and slightly brackish water does seem optimal. This is a lot like Mollies for example, which may be freshwater fish in the wild, but unquestionably are easier to keep in brackish. Because BBGs are very difficult to keep well fed, I'd not keep them in a community tank.> My water is liquid rock. What are your thoughts on this community and any numbers you may think appropriate? Are there any other species you might include instead? <Almost anything that doesn't explicitly need soft water should thrive. pH stability is more important than pH value in most cases, and people routinely keep all sorts of things in hard water conditions. With Threadfin Rainbows, I'd be looking at Corydoras (and their relatives, like Aspidoras and Dianema) in terms of bottom dwellers. Kuhli loaches and small Loricariidae such as Whiptail Catfish would also be appropriate. You might also opt for some surface fish like Halfbeaks. Tetras and Barbs are best avoided because of potential problems with fin nipping, but Rasboras and other small Rainbowfish are certainly an option. Livebearers are certainly a possibility, though some Goodeidae are fin nippers so choose with care.> And since I have your attention, I was reading on here some time ago about separating swordfish fry before the appearance of the sword to prevent inbreeding. So I immediately set up another 10 gal to do so. But I realized when I was trying to sex them that they appear to be all female! Is this a probability? <No. While the idea that Swordtails change sex is widely held, there are actually no scientific studies that backs it up. It is much more probable that aquarists mistake undeveloped males for females. Male livebearers don't develop their sexual characteristics until a certain age (usually around 2-3 months depending on the species). Obviously until the gonopodium is formed they cannot fertilise the females, so you don't need to separate them until that time.> Or am I missing something like the triangular fin I am supposed to be seeing on only the females? Is the differentiation not as great in fry as adults? I ended up separating by size as it seemed the best alternative at the time. Since I was having so much trouble purchasing healthy vibrant red swords I decided to keep the try of a lone surviving, vibrant female. The batch was small but healthy, I have not lost any and they are about 5 months old. But still, not a sword in the bunch...I was hoping for some nice deep red males for another long term plan. <If you have just 5 fry, it is statistically possible, though unlikely, they are all one sex. But if the fry are less than a couple months old, you can't sex them anyway.> Thanks in advance for your help Aileen <Good luck, Neale.>

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