I bought a glass knife fish 3 days ago and I havent been able to get him to eat. They were feeding it frozen brine shrimp at the lfs. I have tried using frozen brine shrimp, frozen blood worms, earth worms, and flakes and have tried feeding both at night and during the day and I still can't get him to eat. He seems to be looking for food when I turn the lights out but won't go for anything I offer him. Any suggestions?