I find the best way to get good growth out of fry is to stick to a less more often formula. This applies to food, water changes etc. I feed small fry 4x daily in small amounts. I also do small water changes more frequently, usually 10 - 15% 3 x a week. There are also special formulas you can add to your water that add various minerals and vitamins the fish will absorb through their gills which aid in growth. Some of this will form naturally in your aquarium, but a lot is removed with water changes. For the first week and a half to two weeks I usually feed bbs exclusively (for some fry you need to wait until they are large enough but cons are born large enough to eat bbs). Once theyre a bit larger I gradually switch to a staple food, NLS grow formula has worked best for me. Some variety should be given to augment their intake once they're on your staple food. Ultimately though, like with most things in the hobby you will need to figure out what works best for you.
