I have had my blue tang for about a year now in a 135 gallon aquarium. The tang is about 4-5 inches in length. It has just recently developed head and lateral line erosion. I have done nothing different feeding or maintenance wise. I do regular water changes. I tested for nitrates and they were undetectable. He is in a tank with all non aggressive fish, and my tank load is pretty light. I feed with a frozen meat food (brine shrimp, mysis shrimp, or other) every other day, which I soak in garlic and selcon. I feed green seaweed/algae every other day. I feed formula two flake food every day. I also occasionally feed frozen cyclopeeze, and the Borneman recipe for reef food. I have tried to feed broccoli, but none of the fish are interested. Any input on what else I can try? Thanks in advance for the advice.