Just got this guy home Sunday night and noticed a little white mass of somethin starting to form dear his dorsal fin and has gotten bigger since. The other spots on him appear to be the normal blue spots on a YWG. He's mostly been hiding but will come out once in a while and swim around the top and bottom of the tank. I saw him sifting sand the first night we had him. LFS has 48 hour guarantee that will be up this afternoon. Should I take him back?? We also picked up a coral banded shirmp that won't come out of hiding.. is he at risk from whatever this stuff is too?