When can i add my platy fry to my main tank?

[pcam86]

Hi, I've got some platy fry that are around 6 weeks old and was just wondering at what size they are safe to go back into the main tank from the breeding net?

I've got aroudn 15 fry and only about 3 are a lot bigger than the others.

 

[Tolak]

When they are too big to fit in the other fish's mouths.

Tolak

 

[pcam86]

hope i don't misjudge this!