Like some other tangs, Hippos are considered ich prone. I have lost two in quarantine a year ago, and only recently tried another one. This one, a tiny one, I added straight to the tank. He is a voracious eater and even pushes larger fish aside to get some food! So far he seems very healthy.
You wont keep a Hippo very long in a 36 until it is too big for the tank. You will want to get a bigger tank or get rid of the tang when he gets bigger.