I picked up a juvi zebra angel , it has really nice bars. In its quarantine tank it wasnt taking food (flake). after two treatments of fritz expel p, it will eagerly take feeder guppy fry, frozen blood worms, frozen shrimp but will not touch flake ( tetra ). Put it in 3 different tanks with different groups of fish and the same happens, eats anything but flake. How do I get it to take flake ??