What the hell is this!?!? I came home from work to see my YT with fins torn up and a white film fungus on the ratty edges. What ever this disease is it was brought into my tank by 2 new manderin fish. One manderin has died and when I got it out of the tank it was covered in this white, almost firm cottage cheese on its fins. the other manderin is doing fine now after a light battle with this disease. I have been reefing for almost 6 years now and this is the first bout of illness that i have come across.