Did one on my blue hippo tang before I knew any better. Tangster would tell you if they white spot is ick, the FW will just stress him out more and may make the ick worse after you put the (freaked out) tang back in the tank, but who knows - it may help. The only thing that worked for ick on my tang was a week in coppersafe in a qt tank, and still waiting to see the long term results of that. But so far so good. Best of luck with your little brown friend. _________ 55gal, 65+ lbs LR, 60Lbs LS, Coralife 125 ss, Fluval 305, HydorKoralia 2 + 3, 2 YT Damsels, 2 Misbarred Clownfish, Blue Tang, Yellow Tang, Leopard Wrasse, Asstd snails and hermit crabs, skunk cleaner shrimp, 3 peppermint shrimp, emerald crab, and some corals.  | 
first dip ever and on a powder brown tang 
