well, i currently feed himPlenty of water changes and varying the food diet will help. Try mosquito larva, bloodworms, commercial foods, earthworms, etc.
I meant raw shrimps bought from markets. Just remove the exoskeleton and feed them straight to the fish. Of course, thaw if still frozen just like frozen bloodworms. I'd do thrice a week water change if I were you.well the water changes is a given, i do a 25% change weekly, do you mean live shrimps???? if so what kind?