Pregnant platy

[Rickyb]

My daughters pregnant platy is swimming up and down the back corner of the tank I was wondering if anyone could tell me how long before she gives birth

 

[fluttermoth]

You want to look out for the fish 'squaring off', that is developing distinct 'corners' on her belly, almost like she's swallowed a box. Once the fish has squared off, they usually give birth within a day.

This doesn't always happen with young females though, as their litters are normally smaller than a mature female's would be.

Incidentally, if you want to know when she's likely to give birth so you can put her in a breeding box/hatchery, then please don't. Those things are far too small, and can leave the female too stressed to give birth (livebearers can hold on to their fry if they don't feel happy), or cause her to abort the fry, if she's put in too soon. They're also too small for raising fry properly; even the mesh/net kinds don't allow enough free movement of water to prevent toxins and hormones building up.

If you want some fry to raise, add lots of live plants to the tank, both for hiding places and as a source of microscopic food (algae etc) for the fry's first few days.