Are all fish dirty little hussies?

[Kia the Koala Lady]

OK, first, I know jack about fish. But I am moving in with a friend soon who has a 65 gallon fresh water fish tank, with some really beautiful fish in it. He is always complaining of babies tho. I guess I never gave much thought to how often fish reproduce, but now I am curious. Is this really common with all fish, is there a way to prevent it? He is always taking babies to the store to sell/exchange for credit. Is this really common? Forgive my ignorance if this is a really dumb question lol but I never owned fish

 

[Delilah (aka levdubya)]

Unless they are live-bearers, which can reproduce faster than rabbits (or unspayed female cats), your friend must have a really great tank environment. Conditions have to be just right to get egg-laying fish to reproduce in a tank. Even if they do go through the motions and lay the eggs, the chances of them actually hatching and reaching maturity are pretty small.

If they are live-bearers, like guppies, then it's quite common. The females can actually somehow 'store' the sperm so that they can get pregnant even months after no contact with males. Guppies are often used as "feeders" for larger fish since they are so abundant. (sorry if you didn't know that.)

You should ask your friend what type of fish they are, and what happens to the babies he is exchanging for credit.