I've tried everything with my boy (except live/frozen foods. Live I'd have to buy online and they probably wouldn't survive the weather, and I don't think that my room-mates would appreciate me keeping frozen worms in the communal freezer

). I've dropped in every type/brand of flake I have. I've tried shrimp pellets, I read that they sometimes grazed on algae so i added a algae wafer, I've tried freeze dried blood worms. All a no go. I used my fancy brine shrimp flakes with brine shrimp crumbs in it... Nothing.
I think he scavenges at night a bit, so I usually drop some flakes in before I turn the lights out and mostly I can't find them in the morning. He's been eating something all year but since I know he doesn't eat everything I usually feed him once every other day to reduce build up. I even tried veggies to see if that would catch his attention...
He's a strange strange fish.
