That's a Purple Masked Angelfish, Paracentropyge (sometimes referred to as Sumireyakko) venustus. That angel's probably a little harder to keep than the Golden Angel. It's difficult to feed, it can suffer from decompression issues, and it's really shy. It's a beautiful fish, but it's by no means a beginner fish. It takes a lot of effort and research to keep this guy alive. I have one now in my reef, which is also why I didn't put the Golden Angel in there, and I have kept two others in the past. This one and the other two never showed any interest in coral. That's one of the nice perks about them. The only issue I ever had was with my first Purple Masked Angel. It liked to nibble at my Blue Linkia Starfish... My current Purple Masked Angel doesn't bother my Marble Star. This is just more proof that all angels, even from the same species, are different.