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. its friday night – Im drinking a bit and watchin my fish – excited to read about breading Swordtails – sinvce I have a male and female and the femail looks mighty pregnant – confirmed by what I read here.

    so tomorrow im running out and getting a breader box and hopefully will have 9 fry of my own

    excellent – im excited – LOL

  2. Do the swordtail fish lay eggs? Or do they just give birth to the fry? How long after the fry are born can I take the fry out of the breeder box? So, the other fish don’t eat them. About how small are the fry? When they are born? I hope I haven’t asked to many questions.
    Thank you.

  3. Hey curious,

    They just have fry. As you can see from the picture above, the swordtail fry are very small at birth. At about 2cm or .8 inches the fry won’t fit into an adult’s mouth. That’s the earliest you could remove them. It takes about three months for them to become full grown.


  4. i need some advice…my swordtail female is pretty pregnant, but i just don’t know when to put her in the breeding pen. i’m afraid that she will become too stressed and die, and i really don’t want that to happen!!!! please help

  5. Margo,

    It’s probably time to isolate her. You want her comfortable, so if other fish are involved, it’s best to move her.

  6. my swordfish is preg. its my fist time on breeding them , how do i know when to put it in and how long for ., i dont want to loose them .

  7. hi
    my sword tail is definatly pregnant is it ok to leave her in the breeder box (like one shown in pic) until she has the fry??

  8. Hi, I was wondering if someone could post or direct me to a picture of a pregnant swordtail. My swordtail had 9 fry once and I couldn’t tell she was even pregnant. I just thought she looked bigger then the male and I put her in a breeder box to read about them and examine her.. within 5 hours she had babies! So, I want to make sure I can catch it the next time!She is a dark orange/red. Thanks for the help!

  9. Ok, so I found the picture of the female “full of eggs” But I swear my fish always looks like that. Will she stop eating before birth? How long is Gestation? Typical number of fry?

  10. My swordtail had about 19 fry in febuary, so around 6 months ago. 10 of those 19 survived. My question is when can the baby’s start to reproduce?

  11. Hi,
    I need some advice…
    I have 4 swordtails. They are about 1.5″ inches long. They were born about 5months ago and now, two of them have a big belly. I would like to know if they are old enough to breed.

  12. my Sword tail is prego’s and I think she is going to give birth very soon this will be her second time but I watched her last night and she was swimming vertical is this something they do I am very worried.

    Thank you

  13. Hi. I got two female swordtails (a red and a yellow with a stripe at her side) and one male (orage in color and has a stripe but it’s bolder than the females, also he has a shorter [not short] and crooked sword) The yellow female looks very fat in the white part of her belly. Did i feed her too much or is that from the babies? I noticed that after i fed.

    So my questions are –

    1. What’s up with my yellow female??
    2. What is better, the plastic breeder boxes like this one [below link] or the nets??
    3. When do i put my female[s] in the box? How big is the spot going to be when she is ready??
    4. I heard fry are good to put back in at about 8 weeks old. Is this true?


  14. My female has had around 18 fry about 4 days ago 🙂 we knew she was pregnant by the black triangular gravid spot, around a quarter inch long, but she had the fry before we knew it, so I had to catch them carefully to separate them. KAT, the reason your female is fat in the white part, IS due to the pregnancy;)We are using a plastic breeder box, and liquifry to raise the young. I also heard 8 weeks is around when I should release the little blighters, but am not sure, lol

  15. Sadly my female swordtail passes the other day. She very prego too. I couldn’t tell when to put her in the breeder box, so I finally did! And she pretty much beat herself up overnight… Oh well.. I tired. Now I have to replace her ='(

  16. I’m sorry to hear that Karen 🙁 The gestation period is about a month, and you should be ok putting the female in the breeder box within the last week. She must have really been stressed. That sucks.

    If you don’t have a bunch of other fish, you can get by without a breeder box. You just need a bunch of bushy plants to hide the fry.

  17. ok, so i read all about the pregnant fish, and i’m pretty sure mine is. but taking care of fish is new to me (i didn’t even realize i had a male AND female until someone told me!). i have two females and one male, and i have two other fish and a frog in a 20 gallon tank. do i need a breeder box?

  18. sorry, i have more questions! we’ve had these fish for less than a month, how do i know when she became pregnant (to figure out when to put her in the breeder box if need be)? also, the other female follows her around and lingers by her. is this normal? i have three plants and two rocks. is that enough for the babies to hide in?

  19. I have a female Swordfish which I bought about 8 weeks ago. When I bought it I was informed that she was pregenant, she does have the black triangle you described, but still no babies after 8 weeks! I am confused!

  20. I have a lyretail sword and ive raised her fry before but lately when i put her in my breeding tank she hits the tank walls and will not have the fry til i put her back in the main tank. She has her fry every 25 days is there a reason she wont have the fry. the last batch i only had 2 and the rest died and the one before that i had 40 fry that all lived.

  21. Can the females hold the babies in for a certain amount of time after the normal birthing time. if so how long can they and if after so long would it be best to move her back in the main tank to relive the stress.

  22. I would like to know what t he male looks like? I’m trying to figure out how to tell the difference between male and female swordtail.

  23. I have a 55gal tank with many types of fish…a lot of Plecos. I noticed one of my female swords belly was really big. Yesterday morning I was drinking my coffee and watching the fish, and I saw a baby fry born. I immediately drove up to the pet store to get a breeding container so I could isolate the female. She ended up having approximately 50 fry. I had a spare 20gallon high tank, so i filled it a little over half way and put a sponge filter with two cups of gravel out of the 55gal tank for bacteria. The fry seem to be doing fine and the mother was released back into the 55 gal tank. I was not trying to breed but nature took its course and it just happened. So i appreciate the people who wrote in previously because it has helped me learn about raising fry.


  24. my sword fish girl is spending a lot of time in a dip in the gravel under the planting the male is horrering about i thought she maybe ill but she comes out to feed
    also good you let me know are they live bearers

  25. Trade them into the pet store for supplies or new additions to the tanks. I think im going to start trying to breed different fish for a hobby. Im getting ready for a 180 gallon tank that a friend of mine is giving me. And my girlfriend wants to start a 75 gallon saltwater tank. As for the 180 im uncertain if i want African cichlids or a home for our many varieties of plecos. Im looking to breed something that is fun, not to difficult, in demand, and may have a good return. Its not about money but to support our enthusiasm for different types and varieties of fish and their behaviors. My friend told me I should do FlowerHorns. Any recommendations. Im kind of leaning towards plecos since my girlfriend seems to really enjoy the different types. One of the stores i go to said he could sell 150 green sword tails a month if he could get some quality ones. But I haven’t seen any in any of the local shops. And I very rarely see pineapple’s either. So I will keep some males and females to start with and try the local shops.


  26. I was wondering if anyone nows a site that would have info on breeding between different types of swords and possible color outcomes. I breed a blue male sword and a female marigold lyretail and one of the babies is about 2 months old now and has a purple hue around his head on belly with a stripe going vertically around its midline with dark orange on the rest of its body. At this point it shows signs of being a possible lyre tail of some sort.

  27. Hi Nathan,

    A pleco tank could be very interesting. I could picture one with driftwood all over.. not just sitting on the bottom, but longer pieces crisscrossed. There’s so many different types of plecos out there. It could definitely be unique.

    Flowerhorns are obviously unique too. I don’t know much about them, such as their compatibility with other fish.

    In a pleco tank you could add “swimming fish” to liven it up if you decided to, since plecos don’t swim much. Sounds fun.

    Here’s a pic of a Golden Monkey Red Face Flowerhorn.

    Golden Monkey Red Face Flowerhorn


  28. Hi, i have started tropical fish keeping about 4 months ago, i have a variety of fish including, 2 mail swordtails, 7 females, i also had a pregnant, female she had given birth 2 37 fry i have only got 20 left i have them in breeding net, the fry are 7 weeks old but still only about 1cm long how long untill i can release them? Tank size 55 galons

  29. Hi Richard,

    I’d wait if you have any fish bigger than those swordtails. It also depends how well planted your tank is. Are there hiding places for the fry?

    Hornwort is a good plant for this.


  30. Hi, my female sword had 37 fry about 8 weeks ago but they dont seem to be growing very fast i feed them 3 or 4 times a day with growth flake am i doing something wrong? or do they take a while to grow?

  31. i have a 55 gallon tank with 3 angelfish, 3 columbian red tetras, 2 gouramis, a red tailed shark, a pleco, a killifish, and i just got 2 female and 1 male swordtail. im wondering if so many fish will stress out my female swordtails which i hope to breed. did i overstock my fishtank, i have 14 fish? please reply, thanks

  32. Hi Mariah,

    The number of fish you have is fine, but when that red-tail black shark grows, it will become very territorial. Give it plenty of room.

  33. oh hi again, im wondering how long and how i will be able to tell my swordtail is pregnant, besides the gravid spot.

  34. I bought my only swordtail less than a week & it look pregnant but i wasn’t sure. the other fishes were so against her in the tank, attack her or something. For precaution, i put her in the hatchy floating tank. to my surprise it had 15 fry.

    Q: How long does the fry takes to grow into an adult swordtail?

  35. Hello,
    this message is for all the people who wrote in about putting their preg. female sword in a breeder container. If you want your fish to survive and/ or not drop her young prematurely, go out and buy one of those small round-shaped flat bowls for beginners (abt $12 and 3x the size of a breeder tank), add Java moss to the bottom and make sure the temp. is not higher then 88°. The plants in the bottom will help prevent her from eating her fry and the warmer temp. will help induce labor. If you add an air stone, make sure the pressure setting is on low so the bubbles don’t interfere with her giving birth. Don’t use the small breeder tank on swords. Not many will survive the drama. Hope this helps you guys. . .

  36. hello, im wondering how long it will take to tell if my swordtail is pregnant. i have 1 male and 2 female. nether of the females looks pregnant. iv had the male in the tank with the females for about 2 weeks. is there something wrong? should i buy another female? i want them to get pregnant.

  37. I have a red swordtail which is realy fat and asume is pregnant i placd her in a breedn net. I lukd at her belly and cant c a blackspot duz this mean she is nt pregnant.she is going up and dwn the breeding net al day

  38. Hello There. My name is Monica and I’m in charge of keeping the fish in my school aquariam. It’s a relatively small tank with only 6 fish as of now, but we’ll be getting more soon. When we went to buy our fish at the local store we picked out 1 male and one female Blue Hawaiian Swordtail fish. Being teenagers and not knowing what we were doing, we simply picked the biggest fish, and it turns out the female was pregnant. I told the Librarians, the teachers overlooking the fishtank, but they didn’t believe me. So, two months later, she just had some fry. There are about 18 of them and I managed to get them into a breeded box that I had bought personally. I read somewhere to feed the fry crushed fish food, and that seems to be working so far. What I need to know is some more information about care for the fry and breeding. I heard that certain aquariam fish, once pregnant, can have multiple births within a certain time period. Will my Hawaiian Sword have more fry? and when will they be expected? Also, how fast will the little ones grow so I can release them back into the tank?

    Thank You for your help and I may be back with more questions later.

    Monica, Hamburg High School

  39. Hi Monica,

    Congratulations! hahaha

    Your fry should be ready to go back with the community in about six weeks. I’d suggest feeding them something like Hikari First Bites. Yes the female can give birth again without being in contact with a male for months after that first birth.

    Good luck… Mike

  40. Hi im breeding red sword tail 2 pairs they give about 6 fry i have natural plant and snials inside the equarium i can breed them with their parents or they will be eaten and how often i feed them twice or more even

  41. one of my swords just gave birth to some fry. she did it in the middle of the night and we didnt know this one was ready to have her babies or if she was even pregnant. she is a solid red-orange color so i couldnt see a gravid spot. we were able to save 11 fry. i have a black female whoi know was pregnant, the other 2 orange i wasnt sure and a deffinate on my pineapple sword. my question is are black sword babies born clear or black? i have the black female in the floating breeder because her belly seems to have squared off. but looking at all of them today they all seem smaller. it could just be my eyes playing tricks on me though. hopefully someone has an answer for me. email me at vdubgirl4u@yahoo.com if you do.


  42. I have a male and female swordtail fish. It looks like my female fish is pregnant! I still don’t see black dots, but speedo (my female fish) has been eating a whole lot! Is she pregnant or is she just getting fat? I know all about breading swordtail fish, but is she ready?

  43. Well I started a 29 gallon tank for my son and i have 2 swordtails(1male 1female),2 mollys(1male 1female)2 goldfish, pleco,1 small shark, and a tetra of some kind is that too many fish?
    Also my female swordtail was in labor and had 2 fry so I grabbed a 2.5gallon tank I have and set it up with water from my tank. I put the 2 fry in the tank because I didnt want them eaten by the others when I went back to my big tank minutes later my female was dead. Did I do something wrong?

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