i have a 3.5 in naso tang i have had the fish for 3.5 months he is fat vibrant and eats and swims like crazy he was in qt for 3 weeks before he went into the big tank about a month ago i noticed a raised bump on his side which was a little darker in color didnt think much of it about 2 weeks ago it has developed into a hole in his side it is not pink or fleshy or anything it is just a hole and he is vibrant as well and he still is happy swimming like crazy eating like a pig and does not seem to be bothered what so ever by the hole in his side not sure what it is or what caused it i have other tangs and stinging corals like hammer and torch i feed formula 2 flakes pellets and nori every couple days all fish are fat happy and healthy