Hello, I recently bought a blue tang and two chromis everyone is eating and looks well but my blue tang has white scratches all over his body I don’t believe it’s ick or a bacterial infection but it’s very strange I haven’t added anything into the tank for 7 months all the other fish are doing well and everyone is eating and swimming. The other fish in the tank are a bi color parrotfish, a fairy wrasse, two small clowns, and a pair of blue chromis. I got the chromis and the tang from the same tank and they are doing well. My levels are PH: 8.3, Ammonia: 0, Nitrate: 0, Nirtite: 0, Salinty: 1.024. Attached are some pictures of the fish. Sorry for the bad quality but looking at it now the scratches are only on his sides they are a bit spread out he is swimming and eating well.