NLS Grow pellets are great. They are like .5mm or something. I feed them to most fry 1/2" - 3/4" and up. I use that and ground-up freeze-dried blackworms almost exclusively when growing out SA cichlid fry.
I use NLS grow, small fish, and Thera-A. Brine shrimp. I got some earthworm flakes from eBay that are supposed to support growth. In the past I've used ocean's nutrition veggie flakes and had good results. Variety is the key. Good luck
you gotta go mad scientist on them,
get yourself a coffee grinder aka bud buster toss in some pellets some flakes freeze dried bloodworms whatever your into and turn those puppies to dust maybe even a few veggie wafers
or if you have a food processor you can grab some shrimp,prawns night crawlers and hit the dollar store grab some ice cube trays and blend up some meat cubes for the babies , crickets whatever floats your boat