Swordtail Fish

Full of eggs, and relaxing in her plastic breeder box, Statico's female swordtail (below) will soon be giving birth to young fry. Adding these live-bearing fish to your peaceful, community aquarium, make a welcome addition.


Many popular Swordtails (Xiphophorus helleri) found in pet stores are hybrids, and come in assorted colors. Marigold, Black Nubian, Pineapple, Neon , Red Wag, and Red Velvet Swortails, are just a few commonly found varieties of this species. You might think the name comes from the sword shaped caudal fin protruding off the lower end of the male. Actually, the swordtail name is derived from the male's anal fin. You can determine the sex of the fish though, by the "sword" shaped fin. Male swordtails have one. Females don't. Notice the lack of this on the female swordtail in the picture. If you're interested in stocking the swordtail in your communty fish tank, keep the following in mind:

  • Minimum tank size is 20 gallons.
  • Tank Parameters: 65-82 degrees F; pH 7.0-8.2; KH 12-28.
  • Swordtails are Omnivores.
  • Peaceful fish perfect for community tanks.
  • Grow to 4" in length.
  • Easy to care for.

As live-bearing fish, the aquarium hobbyist can try their hand at raising fry. You can learn more about swordtail breeding here. These fish are able to reproduce in high numbers. Unfortunately, in the wild, they have become a nuisance in some countries where they were introduced to an area not indigineous to the species.

I've had the swordtail fish in my own aquariums. They are very pleasant, and swim quietly around. You could easily keep them with the Guppy, Dwarf Gourami, and I have even stocked them with Tiger Barbs.

11 thoughts on “Swordtail Fish”

  1. my female sword fish has not long had 12 babies they are a week old-june 23rd, but the female still looks pregnant and got the black spot on her, do u think she might still be prgnant? and how long after can she get caught again?

  2. I never tried breeding swordtails but a few years back I put a male and a few females in a community tank and when I noticed one female was getting quite plump I put her in a 10-gallon tank by herself. After a while she was joined by innumeral little ones that miraculously dropped from within her,unfolded themselves and began swimming freely around. Unsure as to their safety – having previously kept guppies – I put the female back in the community tank.I kept a few of the prettier ones and traded off the remaining ones plus the babies from one of the other females for a betta.
    I figure I got the best of that deal as I didn’t have the patience or time to raise these beautiful fish to their advantage.

  3. Hi, I have a 5 gallon fishtank with 1 male betta. and three swordtails, 2 females and 1 male. I have had them for about 4 weeks now and they are doing fine. I wanted to know if I could get more fish to put in my tank, or if I add anymore, will it be overcrowded? One of my females is pregnant. so should I just let her have the babies and let the babies get eaten? I was thinking of getting rid of one of my females, so that she wont get pregnant too. Is it better for the swordtails to be a pair, or keep it how it is? Thanks, John Kelley

  4. Hey John

    I would not get any more fish. There’s plenty in that 5 gallon tank now. Don’t forget your water changes, which should probably be done weekly.

    Well if you don’t seperate the fry from your betta, nature will take it’s course, and your fry will become someone’s meal.

  5. I recently purchased 4 swordtails ( I male & 3 females). My question is – how big do they have to be before breeding ad spawning take place, and is it ok to keep all 3 females together when they are ready to give birth?

  6. I have 1 male and one female swordtail, they had babies and I wanted to know
    when the male babies will get their tails?

  7. HI my pineapple sword fish is pregnant her belle has gone a white colour and a black patch has appeared shall I put her in her breeding box now or wait any idea how far she is off



  8. so i have a swordtail that is pregnant how long can i leave her seperated in plastic hatchery thing since i dont know when she will give berth ? anyone knowing this please email me at hercules -at- woh.rr.com …same with mollys can you leave them in the plastic thing to long or will it stress them out?

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