I have a calvus In my mbuna tank and I found he wasn't eating flake and the pelets were too big also. I started feeding them Emerald Entree and they all love it. It's an omnivorous formula with spinach, mysis shrimp and spirulina algae. He Is just as fierce as the mbunas when I feed them this and he gets more than his fair share. It's a frozen food that almost every pet shop has.