Check for elevated nitrates. The fish may also be getting nourishment from grazing off the rock work. It's not uncommon for some fish to refuse foods the first few days. Try ofering a variety of meaty foods; finely chopped clam, mussel, sponge based foods, mysis, blood worms, Marine Cuisine, Emerald Entree and other frozen foods. Also try nori on a clip. FWIW, the tank is on the small side for one of these fish. Even the dwarf angels are pretty active and fare better in larger systems.