Recently my potters angel which has always been fat. And I mean fat. Is hanging at the top of the tank. He has some fin deterioration. Actually losing the dorsal fin. Loss of fin Getting worse over past days. Also under belly has loss of tissue . Water parameters are all good. All other fish good abs eating fin. He is not being Harassed by other fish. Tank is Sps dominated with angle fish and wrasses. Was going to hit tank with chemiclean which is used for Cyno but I believe is a antibiotic