Looks similar to:
Neoglyphidodon polyacanthus
Or maybe:
Neoglyphidodon bonang
I take it yours is a baby? If I had to guess I'd say it is a juvenile N. bonang, AKA Ocellated Damsel.
Note that most damsels from the Neoglyphidodon genus are nasty as adults and usually get to be pretty drably colored. But, enjoy that cool baby while you have him!