Brine shrimp for guppy/molly fry?

i have about 40 fry (some guppy, some molly) and i just bought a brine shrimper box thing that's supposed to hatch the eggs and then the baby shrimp swim up into the light and then you dump them into the tank... some have hatched and they're really tiny and when i put them into my fry tank (seperate than my regular tank to try to save as many as possible), i can't see them and my fry don't act like they can find them either... is there a better way to feed them? if brine shrimp are really the best food option, is there a way to grow my own in another tank? i'd appreciate any and all information about this. thanks