Just make sure the water stays clean and feed the parents like you usually would. The parents will expel small pieces of food for the fry from their gills. Convicts are very good parents. Oh and once they start breeding they won't stop lol!
Cons are pretty good parents, leave them alone for a bit and watch them. The parents should raise them. At about 1/4 inch you can pull them and put them in a 10-20 gallon to grow them out.