I have one. I just got him on Friday. Powder Browns can be sensitive to acclimation. Mine has only just recently, like today, started nipping algae off rocks.

Powder Browns are suseptible to ick. If you have a UV sterilizer I recommend running it for a few days before you get the tang, then leave it on for a week or two, just to get him through the acclimation with as little ick as possible.