Inbreeding Swords -- Will They End Up With Three Eyes Or Two Swords?

Discussion in 'Swordtails' started by baltimoregal, Apr 11, 2017.

  1. baltimoregal

    baltimoregal New Member Member

    I have a pair of swords, both rescues, one male and one female from different tanks. They have been in a 36 g community tank with mostly tetrasfor the past four months. They have had 4 fry that have survived in the past month. My concern is leaving all of them together because they will eventually inbreed. Or is this normal in the tropical tank fish world? How is this type is situation normally handled? IMG_2037.JPG
  2. BottomDweller

    BottomDweller Fishlore VIP Member

    If you always remove/rehome the fry it won't be a problem.

    If you want to keep the fry with the parents and breed them indefinitely you need to remove some fish and replace them with unrelated fish every so often.
  3. Polyrhythm

    Polyrhythm Valued Member Member

    You won't end up with three-eyed fish, but after too many generations of inbreeding the fish will be born with more deformities, have weaker immune systems, won't live as long, birth complications, etc.

    Breeding a fry with its parent for example won't immediately cause those issues, so as long as you add in new fish every now and then you'll be fine.
  4. chromedome52

    chromedome52 Fishlore VIP Member

    Inbreeding in fish is not the problem it is with mammals or other higher forms of life. A friend of mine had a population of Swords that started from a single pair, and was line bred for over 50 generations with no deformities or loss of fecundity. He stopped counting at 50, but continued to breed them for many years after that.

    Adding new fish into a line can sometimes be more of a hazard for introducing genetic deformities. It can also screw up your lines if it brings in other genes you don't want contaminating your pure line.

    Suffice to say, it is nothing to worry about for the average aquarist.
  5. Alhana

    Alhana Valued Member Member

    I think a lot of that has to do with the gene pool you started with. Having a few more genes to splice in there is probably better in the long run than just starting with two. I had a friend who had just two guppies and in less than a year he had a lot of fish with severe curves in their spines mainly due to inbreeding.
  6. chromedome52

    chromedome52 Fishlore VIP Member

    Yes, if you start with deformed fish you get deformed fry, but mostly the curved spines are from environmental problems, not genetic. I seem to recall the lack of iodine can cause that, but it could be some particular minerals missing, or poor nutrition.
  7. BettaPonic

    BettaPonic Well Known Member Member

    From my understanding swordtails are pretty tolerant of inbreeding.
  8. BeanFish

    BeanFish Well Known Member Member

    If you do proper culling you should not have a single problem with inbreeding. Like yeah, maybe te fish inmune system will suck, but it does not matter anymore because they get meds, stable temperatures etc...
    I dont know where the notion that inbreeding is bad comes from, a lot of fish people love are the result of inbreeding.
  9. BettaPonic

    BettaPonic Well Known Member Member

    You still have to worry about recessive genes, but I agree inbreeding isn't all bad.
  10. IRTehDar

    IRTehDar Valued Member Member

    Youre going to end up with a bunch of fry that are siblings. The next generation is going to be mostly cousins. The generation after that they will be second cousins. Given that you said that you got the first 2 from 2 different sources im going to vager they are probably not related to begin with so they have seperate family trees behind them. Where mammals for the most part are predisposed to seeking unrelated mates, many fish have evolved with greater resistance to inbreeding issues. In particular lifebearers are highly effective at colonising because a female who accidently swam close to her brother once can produce a stabile population of healthy fish. And you started with 2 unrelated fish. Maybe if you can source a second female from a different source you shouldnt have any cause for concern.
    I started out with guppies and they are still popping out new colourations i didnt even know was in their genepool.

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