Hi,
powder blue tangs get quite large and are very active, do not get one unless you have a tank at least 180 gallons, or plan to move him into one when the need arises. Also, they are very prone to ick. I have on in my 180, he's a great fish but he comes down with ick very easy and is also a very active swimmer. I also have a Yellow and Sailfin tang with him.
Tom