The key is to Feed a variety of high quality food such as a combiination of baby brine shrimp, finely crushed flake and veggies 3-5 times a day. Only feed what they will eat in a couple of minutes and clean out any remaining food.Ensure the tank is large enough to allow the fry plenty of room to swim until they are at least 1" iin size. Lots of clean water and just keep the temp constant. HTH
How big the tank is does make a difference in growth of fry, i had mine in a 1 gal (all i could afford at the time) then bought a 5 gallon just for the fry, they grew a lot bigger and faster. Not sure about temp. but i think it would help they fry grow better. As for food, i heard if you feed them hard -boiled eggs that they will grow faster with the protien in the eggs . Not sure about speices though.
Hope this helps