I've feed him blood worms every day and have supplemented with brine shrimp & flake. I know that he's been getting food because i hand feed him
instead of flakes try to get him to eat high protein pellets, mine loves hikari carnivore pellets and even goes after pieces of silversides. Sounds like nothing is wrong, they grow slow and steady as others have said. dont be afraid to starve him for a few days for him to try new foods.