I used to have a selfin tang . When I bought added it to my aquarium, it was a lovely fish and was completely healthy. After that I added a neon velvet demsel. I was completely surprised when I saw demsel hitting it's face with it's tail and my tang was happy(as when demsel do that it always stayed in its white colour). Then the problem started after 1 week, it started itching and started developing to develop hole around its eye area. Then I started to search on internet about the cause and at that time I came to know about reef2reef website. It was fantastic I got every information here and I came to know that I can't do anything about it as it has no cure. Only thing I can do is give it a good nutrition. I checked stray voltage, running carbon but nothing was going wrong. Then, I decided to give it varied diet. After that I kept that tang for 4 yrs and finally it died. The day it died, it seemed to be happy. I feeded it only 3 min ago! I was near it when it died. It was swimming and playing with demsel but suddenly falled. I checked it and found that it was died (as I have heard that tangs love to play dead). Few photos are below. Will post vedio when my phone will come back after repair. See how playful it was. It was one of my best fishes!