I recently put a 3" blonde naso tang in my tank and he only wants to pick at the rock. He's ignored sheets of nori, frozen food (mixed variety), and live brine shrimp. He is very active and appears healthy, but I am concerned that he won't eat anything other than what's on the rocks. I'm not sure what he's finding to eat on the rocks because they are mostly coraline covered. I'm sure he's finding something, but I don't know if there's enough to sustain him. I've tried soaking the food with a garlic additive, and don't know what else to try. Any ideas? When should I get concerned?