My yellow tang, that I have had for about 4 years now, is in distress. Red patches appeared on it back in December so I treated it with Seachem Metroplex for about 2-3 weeks and things cleared up. Last week I ran carbon and did a water change thinking it was cured. Today the red patches reappeared. It is constantly either in hiding or out searching for the neon cleaner goby to climb on her side. It seems to provide some fleeting relief. Through all of this time the tang's appetite has been strong. It was eating everything: mysis, bine shrimp and seaweed. Today is the first day it swims past food looking for the goby instead. Any advice? Should I try Kanaplex or something else? I was guessing it was a bacterial problem. Could it be uronema?