as title says i have 3 tangs 1 yellow, 1 sailfin, 1 powderblue, now the yellow & sailfin are healthy as a horse. but my powder blue is covered in white spot when bought it was in perfect health any idea how i can get rid of this. iv tried using oodinex which cures most common skin diseases, but it don't seem to be working any help as its a 8" long fish large & i don't want to loose it. before anyone asks the tangs do not fight chase each other around or bother each other at all, so stress isn't the problem. i use a sump LR canister filter plus 2 reactors 1 carbon 1 rowaphos these keep the water pritty clean as my soft corals are growing like mad so help if you can thanks for the read jack..