RE: Scopas Tang with gray spots
Check your water temp. This time of year water temp. is often an issue and creates enough stress to set off a case of Ich in a lot of tengs. The high humidity in the house is enough to slow down evaporation and cooling of the aquarium.
If this is the problem, and I am just taking a stab at it, then solution is extra cooling (fans or ice in the sump), feeding your tang as much as he will eat, and maybe adding garlic to his diet. I noticed my tanks are running cooler today, probably because the humidity has dropped, so if there was a temp spike earlier this week you may not have noticed it. I had to turn on my emergency fans I use when this is an issue. I over designed the cooling fans in my tank for this purpose. The only time I have a problem is in the spring and fall when the windows are open and its a bit muggy like it was earlier this week.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano