Platy fry - when safe to move with adults

[BobK]

Hi all. I have some five week old platy fry and I was wondering when it is safe to move them back to the adult tank. They are about 1/2 inch long but they look to be plump enough and quick enough not to become lunch. Also, at what age can you sex them? I have only two at that age and they both look to be female but I'm afraid it might be too early to tell. Thanks.

 

[WILDER]

Usually once the fish is big enough not to fit in another fish mouth, you should be able to tell the sex now of them, also you will have inbreeding in the tank that will weaken the strain if you put them back in with the parents.

 

[Def]

You won't be able to sex them for ages yet. It'll take about 2-3 months before you can sex them from body shape, and 3 months or so before you can spot a gonopodium.

And yes, you can put them in the main tank now. Distract your adult platys with some food or something first, otherwise they'll chase them.

 

[BobK]

I want to put them in a tank with just females. At what point are they sexually mature regardless of whether or not you can sex them. In other words, if you can't visually see if they are male or female, can a male fry still impregnate an adult female? I'd like to prevent inbreeding if possible.

 

[WILDER]

they can come sexually mature when they are quite tiny as I read it on a forum today.

 

[Def]

Males cannot become sexually mature until a gonopodium forms. If you can't sex them by bodyshape (you'll figure it out as a few mature, becomes easy when you've seen lots of them), I suggest you put them all in with the females then keep a close eye. Better than mixing potential females with males currently, which will probably result in breeding.