Guppies do well with flake powder, but grow much quicker with newly hatched brine shrimp... feed them in small containers until you can see round, orange bellies. They will grow fast. As for what the best ratio of males and females, 1 male per 3-5 females will work, but depends on the purity of your strain and whether you want to improve your strain or breed for show quality. Breeding guppies is easy, but breeding for show or for purity is not so simple because there are many color and shape genes involved.