When fry are born, how will I know which are male and which are female?

Question

I want to seperate them while they are still young so I can be sure the fry won't get pregnant. I know they have to be a certain age to get pregnant but the earlier I can seperate them the better.

So any suggestions to finding the gender?

Answer 1

You can't tell them apart until the are sexually mature.  They all look like females for the first couple months.

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Answer 2

This is very rarely possible with fry.  You don't have to worry as you have time before they reach sexual maturity.  I would need to know what species you are talking about to provide more help however.  The most common being brought up is the guppy, and they take weeks to reach sexual maturity.

Answer 3

you have to wait until they get older if you want to be sure which is which