How big is he?
What are you feeding?
My 12" SFE ate PE Mysis daily when I fed the other fish he was housed with and then got fed ghost shrimp enriched with spirulina and/or silversides every 2-3 days. I successfully kept him with peppermint shrimp and I attribute it to him being well fed. The hand taming also made him much less aggressive.
I fed more often, but smaller amounts when I was hand taming him.