My purple tang has only been in my tank for about 4 days and little white spots have started to appear all over him. I'm guessing he has ich what's the best way to treat him without taking him out of my tank? He's in a 120gal with a lot of live rock so it would be a pain to take him and the rest of the fish out of the tank. The only other fish in there so far is a yellow watchman goby, a diamond goby, and a small wrasse. somebody please help me treat him without taking him out!