keep some more young girls, so you have 20 or so for 10 males, and they'll drop at least 400 fry a month. Should be plenty left after they've eaten some
If you want to increase their survival in the time between being born and moved to the other tank, fill it with lots of plants. I have a strip across the back and the two back corners packes with plants that have leaves from bottom to top, then i have duckweed floating, its horrible stuff to get rid of but it covers the surface and the roots hanging down mean the fry can swim all through without being eaten. Can leave the fry in for a few days and still catch 30 or so from each batch, even though there's rainbowfish and siamese fighters etc in there too.
Also they nearly always have babies in the morning, a couple of hours after the lights come on, so if you think ones about to have babies check about lunchtime and they should all be there swimming in a group in the corner.