Please visit our Sponsors
FAQs on the Swordtail Stocking, Selection

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

Related FAQs: Swordtails 1, Swordtails 2, Swordtail Identification, Swordtail Behavior, Swordtail Compatibility, Swordtail Systems, Swordtail Feeding, Swordtail Disease, Swordtail Reproduction, Livebearers, Guppies, Platies, Mollies,

Platy or swordtail; stkg. Poeciliids in sm. vol..s      8/26/13
Hi there,
I spent a long time reading and can't find answers to the following questions. I have a 70 litre tank and 2 X 20 litre tanks but only a heater for the 70 litre
<18 US gallons, i.e., not a lot of water, so stock carefully.>
and one of the 20 litres.
<5 US gal., barely suitable for fishkeeping at all; at most, either a male Betta, some Dwarf Aquatic Frogs or a shrimp aquarium.>
I have only had my aquariums about 3 months.
<Stock slowly, and read carefully!>
I went away on holiday and used the 5 day feeder gel formula food and came back and all fish were well.
<Good. Just for the future, if you're going away for a week or less, feeding isn't necessary, and in most cases, properly fed fish are fine for two weeks without food. Safer than adding holiday food. Why? Because if something goes wrong, like the filter stops or gets blocked and slows down, there's less waste to pollute the tank.>
After being home a couple if days I did a 30-50% water change and then next day I saw a baby fish and realised ketchup my red platy was a lot thinner.
I also have a fat pregnant swordtail female in the same tank(Tiger).  Over the next week I collected 6 more babies from the stones and plants.  The first fish is slightly larger and plain and the others are all striped like the swordtail mother.
<I see.>
Do you think the plain one that is much bigger could be the lone survivor from the platys litter (or what ever you call a brood in fish) and the striped ones are swordtails like their striped mother?
<Possibly, but hard to say. Livebearers of all kinds can delay the development of fertilised eggs, which means that a female can produce fry anything up to 6 months after mating with a particular male. That means the father of your baby fish could have been one of the fish in the pet store.
Hence fish breeders who want particular sorts of offspring use virgin females, i.e., they take some female fry when only a few weeks old, isolate them, and only put them back with a specific male as/when they want to breed from them.>
I also wonder if my swordtail is still pregnant as I haven't found any more fry for a few days but she still looks pregnant.
<Possible, but again, be open minded. Ensure diet is adequate (these fish are largely herbivores, so need a greens-based diet, e.g., Spirulina flake) otherwise constipation is common. Water fleas (Daphnia) are a good laxative. Also be aware of what Dropsy looks like, and keep an eye open for it. It's a common problem when fish aren't kept perfectly well.>
I also just want to mention tiger the swordtail female started off being really bossy and aggressive with everything else in the tank and my first swordtail male hid from her and eventually died.
<Swordtails are aggressive, and your tank is too small for them. Bear in mind Swordtails are fast fish from flowing water habitats, and they can get to around 8 cm/3 inches in length, sometimes even more. I'd keep them in tanks not less than 70, 80 cm long, so realistically, tanks in the 110 l/30 gallon size range upwards. In smaller tanks aggressive fish will often
whittle their population down to a manageable size, and that may well be what you're seeing here.>
I since replaced with a new one who can just barely cope with her. I know this ratio of 1 male to 1 female is not normal but it seems right for her. 
What do you think?
<See above; Swordtails are aggressive and chase each other a lot. Keep two females per male, in a suitably sized tank, and either one male or three, never two because that number seems to end up with one bullying the other.
To be honest, in small tanks Platies are better bets.>
I got a lyre tail molly female to be boss and she started off hiding from tiger.
<Mollies definitely do not belong here!
Do read up on these difficult fish.>
I had to replant and move everything around to give all new territories play and this helped them to fit in better and now the 2 play and thankfully mainly leave the smaller fish alone. I must say I don't like the idea of having just one lyre tail molly but think this is working for the individual fish involved. 
<Mollies don't get lonely.>
I think I might sell 6-7guppies and just keep the named male (Albie).  He doesn't seem to Fin nip like the others do but would I have an issue with having 1 male guppy without a female or 2 to hassle in with the other fish?
<Stop. Your tank is already VERY overcrowded.>
The guppies are brothers and sisters so  I don't want these particular girls as I don't want to inbreed them any more as I got them from someone who has inbred them heaps.  I would want a new gene pool even though they are very pretty.
8 neon tetras
2 female platys
1 male platy
1 female swordtail
1 male swordtail
1 female lyre tail molly
2 peppered Corydoras
1 bronze Corydoras
2 Bristlenose catfish
7-8 nearly grown Guppies including named male
Thank you so much for your help
<Do read:
And follow the links. You have a very small tank overstocked with fish with different water chemistry requirements (e.g., Neons need soft/acid while Mollies and need hard/alkaline and possibly even brackish). Some of these fish are quite hardy (e.g., Corydoras) but others are notoriously difficult for beginners to keep successfully (Neons, Mollies). Cheers, Neale.>
Re: Platy or swordtail     8/26/13
Hi Neal
Thank you for your advice.  The only thing that I can't really understand is whether one guppy is okay in the communal tank rather than the current 6-8 or whether I need to keep a female to keep him happy?
<Guppies are fine on their own when kept with appropriate tankmates. Adding females (plural) per male Guppy is of course doable, but not necessary, and males harass the females in small tanks.>
The 20 litre tanks are 1. for raising babies and 2. for breeding food for my tank i.e. brine shrimp or Daphne.
<I see.>
What is Dropsy? Is there a link about it?
<It's a symptom rather than a disease. Fluid retention inside the body.
Indicates all sorts of different things, but typically bacterial infections and/or organ failure. Difficult to treat unless caught early. Very characteristic of Dropsy is the "pine cone" effect seen from above, as the scales of body stick outwards. Do start here:
Take care
<Will do, Neale.>

Xiphophorus; reproduction, stocking     6/4/12
Good evening! We have a 15 gallon tank with the following inhabitants: 4 zebra danios, 3 blue fin guppies, 4 White Mickey Platy's (2 male, 2 female), 3 Sunburst Wags (1 female and 2 males), and a small catfish.
<What kind of catfish? A Corydoras? They are social fish -- get a couple more, at least. Your tank is already pretty well stocked though (and I'd argue the Danios are too active and big for it anyway) so you will need to focus on water quality.>
Our sunburst wag, Momma, gave birth about 3 weeks ago; we were able to recover twelve of the babies; currently in a 10 gallon tank and thriving.
Today, we saw at least 2 new babies in the original tank! We're pretty sure they're Momma's babies because she's been behaving like she did a few weeks ago.
<Any/all of the females will be pregnant since you've added males, so I'd be open minded about who's the mother.>
She seems so stressed out right now from giving birth so soon. Can we put Momma into the other tank, with the original fry?
<If you want, for a while. But 10 gallons is too small for adult Platies.>
Also...is there a way of avoiding breeding, by say...having all females or all males of a particular species?
<For sure. Keep virgin females and you'll be fine. After mating though the females may produce more than one batch of fry, so just removing the males today may mean it'll take many months before the females are "empty" of fry.>
Thank you so much, Bryan and Kimberly
<Cheers, Neale.>

Just one swordtail with male Platies   9/11.5/11
I have a 46 gallon Bowfront with three male Platies. Yesterday I bought one male red velvet swordtail. He is ignoring the male Platies, and he has been going up and down the side of the tank since yesterday. Will he calm down soon? I do not want to get any female swordtails due to the endless babies.
Would it be ok to get a second male swordtail or would that lead to aggression??? I also have a 20 gallon long with female Platies, but I would not want swordtails in with them as the tank is smaller and they are so gentle. Thank You!!!
<Greetings. It's worth making two points here. Firstly, Swordtails and Platies come from different habitats, so what they need to be happy are different. Platys inhabit still water, like ponds, while Swordtails come
from flowing water habitats like streams. So keeping the two in the same tank will demand compromises, and these may not work well. A Swordtail wants a spacious tank with a strong current and plenty of swimming space.
Secondly, Platies and Swordtails are both hybrids nowadays, and consequently very difficult to predict. Usually, Swordtail males are aggressive while Platies are somewhat less aggressive, but there are
exceptions in both cases. Hope this helps, Neale.>
Just one swordtail with male Platies   9/11.5/11

I have an air pump with a long air stone. Is that was is used for water circulation??
<It will work for this just fine.>
Is 46 gallons too small for them???
<Nope, that's a good size for a male and two females. If you want just males, keep at least 3, but do be aware that Swordtails are extremely aggressive and likely to bully one another, so I prefer to keep just a single male or as large a group as possible, ideally six or more males.>
The water in the tank is cool and hard.
<Good. Both Platies and Swordtails want temperatures between 22-25 C (72-77 F) and water chemistry that's 10+ degrees dH, pH 7-8.>
I was wondering why some fish will swim up the side of the tank and down again over and over??
<Stress, usually. The specifics depend on the situation. Could feel cramped, could be being bullied, could dislike the water quality or chemistry, could be wanting to swim towards a stronger current, could be bored'¦ So essentially you need to go through the list of requirements for a given species, check the conditions in the aquarium, and think about what's wrong or missing.>
Thank You!!
<You're welcome. Cheers, Neale.>

Swordtails, comp. w/ Platies    8/8/11
I have a 46 gallon bowfront. I was wondering would it be ok to keep a few female swordtails in there if they were sharing the tank with two male platies, or are swordtails just too aggressive?? Thank you!!!
<These livebearers will likely mix (and interbreed) fine here, given the size and shape of this volume. Start w/ "not-too-large" swords. Bob Fenner>
e: Swordtails; stkg./sel.: size and comp.     8/8/11
Are there actually smaller species of swordtails?
<Mmm, not really... there are ones that have been stunted, and others that have had fab care, frequent feeding and water changes... that can be HUGE though. There are other Swordtail spp., but these are rarely sold/seen in the trade>
I was in a LFS the other day and I saw some female swordtails that were HUGE. If they were hollow, you could fit eight platies inside them, they were that big.
<Yes; have seen six inch plus specimens>
I am assuming that males would be too aggressive to keep with two male platies in a 46 gallon? I heard they are terrors. Thank you!!
<Domesticated Swords aren't that mean. BobF>

Male Swordtail Terror  6/26/08 Hello Neale and all WWM Crew. Happy Summer to you. <And to you> This is a question on a male swordtail terrorizing the other two in a 125 gallon tank. The end string below summarizes our fish quantity, but recap is 50 fish; community of platys, swords, mollis, Corys. There are 7-8 assorted female swords. There are 3 males; a medium pineapple, a small black (mature, and a large red 'standard LFS' male. All have been in the tank 6 months to a year. The tank has corner pumps, many fake rocks, plastic grass, etc to hide in. Early on the very large red male was boss and would harass the black one only, who has never attained great size. This stopped. All was calm. Now the very large red is no longer the kingpin male. Though not the largest, the pineapple has begun to really harass, chase, and bite the black and the red. <Strange> Both are becoming skinny, show fin loss, and hide in corners. They can't get to food without being chased the length of the tank. They are not diseased in any way. With 7 females, we thought we were ok; decided to let nature take its course over the last two weeks. But we couldn't stand it, the pineapple is downright being a brute. Today we isolated the pineapple in a large plastic colander in the 125 tank. <Good move> Here are what we feel are our options: 1. Buy more females and hope for the best in the 125 tank. 2. Move the pineapple to a 10 gallon empty fry tank that is operating, along with two females. Hope he wears himself out and the other two recover and fatten up in the 125 tank. 3. Move the red and black male swords to the fry tank along with 4 females to fatten up. 4. Do nothing and hope for the best. (We feel the two harassed swords will die of starvation if we do this.) 5. Hang the pineapple from a yardarm in front of the other fish as a lesson at high noon. <Heeee! Hang 'em high!> Please tell what you think and elaborate as to the +/- of each option. Many thanks, Rosemary and Don <I would go with #1... and possibly try changing the food. Do look into supplanting what you use with Spectrum pellets... sometimes nutritional deficiency can be a large player in affecting fish behavior. I have found this food to be excellent nutritionally, very palatable (to the fishes!), and a calming influence. Cheers, Bob Fenner>

Re: Male Swordtail Terror/Food, Ratio Males to Females  6/27/08 Mr. Fenner, <Rose and Don> Many thanks for your helpful reply. Our pineapple sword remains in solitary on bread and water pending purchase of more female swords. <Good> Missed asking the question of what ratio of males to females might solve our problem. If 2.33 to 1 is not working (7 Females and 3 males), how many females total would be appropriate for 3 male swordtails in our 125 gallon tank with the current animosity? <"The more the merrier"... at least three to one... Am now humming a modified Beach Boys tune...> We feed twice daily. Always daily Wardly Algae Tablets (Corys and the rubber lips), and alternate Tetra Tropical Flakes with shrimp pellets or blood worms. We never personally thought much of the shrimp pellets, too messy. How does that sound for balance and nutrition? <I'd add some more with greens, or greens themselves...> Anything there a waste of time? We will immediately add in the Spectrum Community Pellets to the mix when we get to the LFS> <Is a great product... as you and your aquatic charges will find> Thanks again and cheers, Rosemary and Don <And to you, BobF>

Re: Male Swordtail Terror/Food, Ratio Males to Females Update - 7/1/08 Hello WWM gang, our problem remains. <Really?> Please see the string below. We made a thorough count and had 8 female swords. The black male died of stress/malnutrition while the pineapple male was in the cage, so after 5 days in the cage we let the pineapple male out. The LFS had zero quality swords this week so we declined to buy. We thought we were in the clear with the 4:1 female to male ratio (8:2 in our tank now). Would add that all 3 males and several females had been in our tank for close to a year. The pineapple male sword hid for a half day after we let him out to play, then began to harass the larger remaining red male sword relentlessly (the red hides behind power filters, more nipped fins and really skinny). <Dang!> We increased feed to 3 times a day to fatten up the male red sword, ensure he could get to food. Added fresh peas to the feed with the spectrum pellets, flakes, algae pellets. After two days of terror, we again put the pineapple male in the cage. The red sword is now totally normal, in the open, and eating well with the pineapple male locked up. <Good> Our other fish count is 7 platys, 9 guppies, 10 Corys, 1 Pleco, and 8 mollies. We are close to our normal imposed limit on fish (50) for 125 gallons. We have good water and can add more female swords if you think it best still. <I am considering suggesting trading in the one male, isolating it permanently or suggesting destroying it> Question is, if 8 females: 2 males does not divert attention of the male pineapple from the red male sword, will 10:2 or 12:2 be better? <Too likely not> What should we do? Should we add a bigger male sword and hope to change some dynamic in the tank? Should we let the pineapple out, let him kill the red one, get it over with, and have 8 females and the 1 pineapple male? <This IS likely what I'd do> We have not had this extreme behavior before, so we are at a loss. Any thoughts appreciated. Cheers, Rosemary and Don <Have seen this rogue behavior a few times... even in humans... BobF>

Re: Male Swordtail Terror/Food, Ratio Males to Females Update - 7/2/08 Many thanks, sir. <Certainly welcome> We favor letting the pineapple out and accept what happens as you suggest. <I see> Our reasons are these: In our area, pineapples are difficult to find, reds are dime a dozen; the red may die anyway given the stress; and the dynamics may change and the pineapple may gravitate toward a female. <Mmm> Strange to us (is it to you?) that for all this aggressive behavior, we have not seen the pineapple express any interest what so ever in nuzzling up to females since we got him a year ago. <Interesting... as a reality and observation... Am given to wonder here. Perhaps this really isn't a "real" male... the genetics/expression of sex and traits, behavior in poeciliids is a bit more complex than humans, companion animals that most people are more familiar with... Perhaps we should "chat" this up a bit> We appreciate your most helpful site. Spent 5 hours last night just reading FAQ's on different subjects, feeding, chemistry, and breeding. Wonderful service to aquarium owners that you have going. Sincerely, Don (and Rose) <Ahh! A pleasure to share. BobF>

Swordtail info. Repro., sel., sys.     11/27/06 Hello every one, <Hey FJ! JustinN with you today> I was cruising the net looking for info on the gestation period of Swordtails when I found your site. Wow lots of info. Great site. My hats off. <Thank you, is appreciated> It's been a while since I've had a serious tropical tank. ( I got into freshwater for a long while ) I've recently set up 3 tanks for tropical fish. 1 show tank 55gal. and 2 20gal. 1 for isolation and 1 as a nursery. plus 2 more are on the way. <Sounds well thought out> Although it's been awhile I think some of your readers might like hear a couple of the basic thoughts I have on this subject and maybe they'll have less problems. <Ok, will post for all to see> 1 - Maintain your ph.. @7.0 no more no less I have found this makes for a better well rounded tank with less stress and less stress means happy fish, and happy fish ( from my observations ) means less parasites. 2 - Double the recommended amount of salt in your system.. the fish don't mind but the parasites do. 3 - Never let the water temp drop below 78f  I find 78-->80 degrees is perfect (for happy fish) 4 - Quarantine your plant for awhile just as you would your fish...before putting them into your main show and/or stable tanks. 5 - If possible feed your fish more than once a day. I like to do this when I have breakfast & dinner. Never feed just before you turn off the light. 6 - Frequent water changes pulling 50% of the water out of the system every 3 months and changing you filter carbon and floss every month (and cleaning the filter itself) 7 - Minimal decorative gravel on the bottom of the tank (less the better) 8 - Know before hand how certain fish will interact with others. 9 - Have a diversity of life in the tank, fish ,snails, crayfish, frogs, plants, well you get the idea. <Not too keen on the idea of crayfish with fish here, but I digress> 10 - Last but not least a nursery tank should be jammed with plants and snails. I know this is all stuff you already know but maybe you could put it in your own words and let the people know. My wife thinks I'm crazy ...and she's probably right, but happy fish can make you happy. Thank you for your time. FJ. <Thank you for your suggestions. We will post for all to see/read. -JustinN>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: