Swordtail Breeding

I've never tried Swordtail breeding, so I asked someone that has, to share their experience. Ian, also know as Statico, has allowed me to use a few pictures, and answered some questions on breeding the Swordtail fish.

FunFishTank: How long have you been breeding the swordtail?

"We've had the sword tails for two months. There are two
males and two females. This is my second group of swordtail fry. The first were
born right after we got the parents and we didn't have a
chance to isolate the mother. Most were eaten by other
fish, and we've had no luck with a breeder *net* -- all of
our guppy fry and our remaining sword fry died in the net,
so we decided to get the breeder box as a replacement."

You can see the fry in the plastic breeder box.


FunFishTank: How could you tell when the female was pregnant? How many fry did she have?

"We could tell the mother was pregnant by the dark triangle
in her abdomen. The swordtails are translucent fish and you
can see eggs and then eyes as the fry form. The swordtails had 9 fry this time."

The "dark triangle" Ian refers to is the gravid spot.

FunFishTank: What did you feed the fry?

"We feed them Hikari "First Bites" fry food. It sinks slowly
and the fry love it."

Check out this one day old swordtail fry! It's 7mm (.28 inches).


FunFishTank: What type of aquarium setup did you use to breed the Swordtail? Were their any other fish in the tank?

"Our tank is a 50-gallon freshwater tank. There are 4
swordtails, 4 white cloud mountain tetras, 1 cardinal tetra,
2 zebra danios, 2 leopard danios. There was one black molly
until very recently, and we plan on adding more mollies

FunFishTank: I've heard that the female swordfish can sometimes die after having the fry. Was your female ok?

"The female looked pretty stressed when we put her in the
plastic breeder isolation box. The box was underwater
(about 1 inch), so I had to feed the mom using a tube from
a ball-point pen. I put the tube into the hole at the top
of the box and dumped some flakes into the tube. The flakes
would sink slowly and she was much happier when fed. She was
fine after having the fry."

FunFishTank: That's good to hear! You've taken some great pictures. Could you tell us how you did it?

"I took the pictures using a Nikon D50 digital SLR camera
and a 50mm Nikkor macro lens. I set the ISO to 800 (I
think) and used a wireless, off-camera flash on its
lowest-power setting. I placed the flash off to the side
with a diffuser so it would light up the box but not blind
or scare the fish."

Thanks for sharing your experience of Swordtail breeding Ian! The two tips about using a plastic breeder box, and feeding the female are good to know.

108 thoughts on “Swordtail Breeding”

  1. Hey Sid,

    Your fish could have already been sick. It happens. As for too many fish…. the rule is 1 inch of fish/gallon. Remember they grow.


  3. Hi, my female sword tail fish already has a big triangular gravid spot for about 4 days now i isolated her in a 2 gallon tank. so my question is, how long will it take her to have babies?

  4. my community tank is about 5 gallons with 1 male sword and 2 females excluding the one i isolated in a 2 gallon tank.

    oh! almost forgot THANKS in advance =)

  5. hi mike.a cupple of days ago i had a fancy guppy that was going to have babys but died to soon. i wanted to get a swordtail male becuas i already have a female but just need a male, could you tell me were you got your breading tank, i would love to know. please right back soon. from summer.

  6. Okay from an earlier post one said their sword fish had 9 babies. sword tails have many many many babies at one time. I use to breed sword tail and guppies at a time. Sword tail can give birth to as many as 80 fry at one time. another post said that the fish can not fit that size fry in their mouth. they can fit the fry in their mouth. that is why the one only found 9 fry. she ate her babies. its survival of the fittest. you would be surprised what size fish one can swallow. they just have to swallow head first on larger fry. new born fry are perfect size for eating. that is why you get the breeding tanks that have a bottom part the fry swim into but the cracks to small for the mother. that way you will find you fry will be a lot more then 9.

  7. my swordtail is in a pond and 2 of my female swordtail is pregnant. can i put them together in a plastic container cause i think plastic breeder box is not fit for a pond,
    and if i put them together do i need to put aquarium air pump?

  8. I’d think you could do that. If it’s a seperate unit, keep up with water changes. If the space is small, and you have an air pump, it wouldn’t hurt.

  9. How many weeks before i can remove my fry to there own tank and put them to my pond with my other swordtail to make sure that they will not will be eaten by my adult swordtail.
    thank you!!!

  10. hi if anyone could tell me how long after a swordtail has there fry can she get pregant again as my swordtail had 47/48 fry about 2and a half month’s ago and they are in a tank of there own now i am almost certain she is about to give birth again i was just woundering if they can get caught about 2 week’s after having the fry. the only reason i ask that is because my male swordtail got eaten by one of my other fish 2 week’s after she had her first lot and can someone tell me how long they are preganant for thank’s ever so much i now this is alot to ask but i would really like to know asap cheer’s katy

  11. hello, do a pregnant sword tail and fry need an oxygen in there own breeding area?even if i put some anarchis in there breeding area?
    thank u.. merry xmas & happy new year

  12. I have two female, one is the baby of the other, and one male. The older of the two females looks pregnant again. (I can see the eggs thru the skin). The younger also looks pregnant, but I’m not sure. Niether looks very large in the belly. How long should I wait before putting them (her) in the breeder tank? The older one had a batch of fry, (the other female I have is the only one that lived), a very long while back and when I realesed her back into the tank the male became very aggressive towards her. I also have Angel fish, one glow, Barbs, Ghost fish, Plecos, and one other I am not sure of the name. Any suggestions you have are always welcome. I think I have the raising the fry thing down, but need to know when to put the mom’s in the breeder tank. Thanks for any help.

  13. hey i got a question: well the other day i got my fish set up in a good sized tank, plants, and a light. I bought red velvet sword tails: 2 females 1 male. Both the females are pregnent ! i wanted this to happen but I don’t know when to put her in a breeder box/ breeder trap. help!

  14. i got a swordtail from my local aquarium and was told she’s heavely pregnant, i’ve put her in my breeding box but as i’m not sure how far along she is how long can i leave her in there???

  15. great news my swordtail gave birth 2 around 45-50 fry 2 days ago it was a very exciting day 🙂 all r doing fine

  16. uhm..
    i would like to ask how long is a swordtail’s pregnancy? i’ve got a female swordtail in my tank and would ask how long do i need to quarantine my baby fry from the adults…

    have a nice day

  17. the males have a longer tail that looks like a sword when my females are ready to have babies or even look pregnet i put them in a ten gallon tank and i also have a ten gallon i put the babies in by there selfs so the dont have to hide from the adultes or get eaten i found that so much easyer oh i also have plants for the babies when the females give birth i got 29 babies kept 5 they were green sword tail s very pretty .good luck everyone.

  18. most swordtail’s are pregnant for around 30 days give or take. i have bred 10 times now, and i love it i have had a 98% success rate of survival the others got eaten when i was a bit to slow. i can tell when my swordtail is pregnant when her gravid spot has darkened and her belly is swelling a little bit. my fish when about to give birth have an almost squared tummy, and will swim constantly up to the surface of the tank then back down to the bottom, repeatedly. that is how i know to get another tank ready and separate her from the other fish. as soon as they are born i remove her from the tank and put her back with her friends. i usually feed the fry a little bit of blood worms when i’m giving my other fish some and really crushed up normal flakes. just make sure though you don’t give them to much as it will pollute the tank which can cause diseases and in some cases death.
    i hope that has been helpful.

  19. i would quarantine them for at least 2 months until they’re big enough to not be eaten.

  20. also i find swordtail’s a little aggressive if in a smallish tank with guppies. if you want a harmony’s tank then get a bigger one with a lot of space that can be split into territories by your fish. if you have any question please write to me at bookwormbec at gmail.com

  21. can oronge sword tails go with out food for four days? im going on a trip and im trying to figer it out

  22. I have a 600l heavilyu planted tank with 6 swordtails (3male 3female) plus many other tank mates. I bought them about 2 weeks ago, and a few days ago i noticed one of my females getting quite fat. then i noticed the dark spot so i decided to do some research. after finding out she was definatly pregnant i put her strait into a seperate tank on her own and blow me, the very next day she had lost her fatness and i noticed about 20 babies swimming around. From what ive read this was very lucky as its really hard to tell when therye gonna drop. i seperated the female strait away and she seems fine. the fry tank is set up so that water from the main tank flows in and gets syphoned back out into the main tank. as far as i know they can be fed crushed flake immediatly. I’ve only ever managed to breed my paradise fish, and this was only recently, they were very interesting to watch! building there nest and watching them court. also from my research i know that swordtails remain pregnant after they have given birth, and will spawn almost monthly, storing the sperm from one mating encounter enables them to have several pregnancies, so i will be keeping my eye on her. she does still have the dark spot near the anal fin and its a few hours since she gave birth, but its not as clear as it was lastnight, and she has lost the round belly, so im sure she has finished spawning for now. Its a really rewarding experience bringing up fry and from what i can tell, swordtails breed more easily than any other fish…. u dont even have to try! I think my female must of been pregnant when i bought her, this is very common.

  23. forgot to add, the pregnant fish is a pineapple sword, and i suspect the male pineapple sword is the father as they have been very close recently. there is also 1 orange wag (male) 1 green (male), 1 gold painted (female) and 1 pineapple painted (female)

  24. ok, i just got 2 swordtails today and i didnt realize until i was almost home that one of them was pregnant. i dont have a breeder box, but the only other fish i have are 2 zebra danios and a plecastymus, could i get by with out a breeder box???

  25. Those other fish aren’t aggressive. You need plenty of hiding spots for the fry, and have to remember the adult swordtails could eat them too. Can it be done? Yes. But it’s more risky without a breeder box or breeder net.


  26. hello ive got swordtails girls and boys i had a litter of fry every month for 4 months running the most she had was 48 one time also ive breed my mollys a couple of times and platys once and plecos now im breeding my guppys
    its so cool waiting and finding the babys in ur tank trying to catch them working out who they came from

  27. hiya,ive got a 65 litre tropical tank,having bought 2 swordtails,1male an 1 female i notices the female was very bnig and i can see the gravid spot at the lower abdomen,i isolated her in the breeder net but see looked stressed so i released her after two days, she still has a big belly an gravid spot but still no babies!! how do i know when she is about to give birth? and can she put the birth off for a matter of time?? please get bk in touch as i do not know when she is about to pop and i just dont want isolate her like 2 weeks before she gives birth if ya know what i mean

  28. I have a male and a female swordtail, and recently have thought she could be pregnant, she just started getting bigger and bigger. Shes not humongous at the mo, but when u c her front ways, she looks abit like a balloon lol. Thing is, i can’t be 100% sure, because i can’t c a gravid spot, and the reason for that is that she is black, (orange on the top) So how do i know if shes prego and not just fat (altho she shouldnt b fat, i dont overfeed her).

  29. can a red eye swordtail fish live a pond with out an air pump but a there is a lot anachris?
    thank u!!

  30. You you could change the post subject Swordtail Breeding | Fish Tank | Tank of Fish to something more catching for your content you make. I enjoyed the blog post however.

  31. I have a question: is it possible for swordfish to have differn’t colored fry? When I mean by that I mean if a red and white swordfish had fry, would the fry be pink once they become adults? the reson is i tried that, and the mother died while preg.

  32. My swordtails just had a brood, thats actually how i found this website. I had a Kribensis African cichlid in the tank with it and the kribensis ate most of them during the night, when they actually came out. But i was able to get four of them out of the tank in time luckily, i am kind of confused on how to feed them. one friend said put lettuce in and stuff will grow on it that they love, but everywere on the internet says just crushed up fish food. The water hardness is very low (i read in a book that helps young fish and plants) and the ph is just right, and im trying to keep the temperature at about 72-ish but i dont have a thermometer for them. If you have any suggestions please reply. Thank you for the post!

  33. I had my male pineapple swordtail for about 2months. The guy at the fish store said he will only breed female pineapples however, when I brought home a female red velvet, he was a happy fish! About two months after that, I noticed an orange fish I never saw before and it was a baby swordtail! It was about a third the size of the mother when I finally noticed it. I couldn’t even tell she was pregnant and I have no idea how many fry there were. The baby looks exactly like the red velvet mother now, I call her a teenager, now about half the size of mom. I don’t seperate my mom at all, I watch the pineapple breed her all the time and I decided to keep it natural as long as mom doesn’t look stressed. May not end up with as many as fast but survival of the fittest is ok by me. Also have baby plecos now! Haven’t even tried for that!

  34. Well i am used to raising Fancy Guppies (and raising swordtails and Platies seem to be the same).. I do it a little different to reduce the amount of fry eaten by the Adults..

    My Green Swordtail female just gave birth to about 42 fry, i stopped counting at 42.

    I have 4 Tank set-ups

    *I have a 2.5g raising tank, heavily planted and some java moss at one end.(gives then organic matter to nip at and also fiding places)

    *I have a 10g plant ONLY tank, that has a lottt of cover and driftwood

    * i have a 5g tank that doubles as a Qurantine tank…

    *and i have a 20g Display tank.

    The 20g is a mixed community tank, once the “loving” is done and the female/s are gravid (pregnant). I will pull the female once i can view the eyes of the fry and the gravid patch starts to get dark and place them in the 10g PLANT ONLY tank if there is only one female at that time (if there are 2 i will put them in the 10g in a divided breeding trap with a open grid bottom… in this case the fry will fall through into the tank and away from the mother… i will also do this if i will be away for more then 24 hours and can’t check every 3-4 hours.).. I check the tank about 3-4 times a day (or every 4 hours). My daughter helps with this part lol. This way you sometimes catch her in the act of giving birth (it’s a good lesson for the kids and also for Adults). The fry are free swimming as sooon as they are born.

    The mother will not start to eat her fry till she is done giving birth (usually 2-3 hours) which falls right in with your “check-ins”.
    Once she has given birth, i take hor out and place her in the 5g tank to relax b4 returning her to the 20g Display tank.

    I then net or syphon the fry from the 10g and place them in the 2.5g where they grow out….. i usually have a batch of fry every 2-3 weeks .

    I let the fry grow out to about 2 months in the 2.5g, and keep about 2-3 from each batch that have the best color and health and thoes lucky ones goes into my 20g Display tank and into my breed stock.

    The rest are given away to friends or sold cheap to local pet stores.

    Hope that helps.. I have pix of the whole deal if anyone would like to see. Please e-mail me at JonRich918 [at] aol.com and i’ll respond with pix.

  35. Hi Jon!

    Thanks for the detailed system! It’s good to get different ideas on technique.


  36. hi there, i know this may sound cruel to some, but have you found it ever necessary to cull any of the young off due to deformities or unnatural growth development? I am new to owning tropical fish, and have just finished setting up and stocking a 90L tank about half a month ago. I have just bought a breeding tank for my pregnant swordtail. I would just like to be prepared for the worst that may happen.


  37. helloo, I have 2 guppy males, and 4 guppy females. one of the females looks pretty pregnent. the belly is pretty big, bigger than the others. and i see the gravid spot, but I dont know when I should put her in a breeding box? please answer me. i realy need some help. thanxx for the answers!! 🙂

  38. i have a female swordtail and a male.
    the female has a large white belly and the male chases her.
    do you think she is preg.

  39. I have 2 male swordtail, 1 female + 16 small ones, 2 butterfly + 4 small ones, 2 plecos. I just got the swordtails and butterfly. Since they came I notices my gouramies have gone missing and 2 of my swordtails and 1 butterfly. Could these new fish be eatting my female fish?

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