What kind of fish is Gill from "Finding Nemo"?

In "Finding Nemo," the black and white fish, freedom-loving Gill, is a "Moorish idol." Gill was voiced in the 2003 movie by actor Willem Dafoe.

The other iconic characters from the movie cover a wide range of sea creatures. For example, Nemo and his parents, Marlin and Coral, are specifically Ocellaris Clownfish. The tropical Pacific Ocean holds over 30 varieties of these fish. Sweet and forgetful Dory is a Blue Tang. Fearful Gurgle is a Royal Gramma. Deb and her "sister" Flo are both Damselfish, though Flo is actually a reflection. Efficient Jacques is a Cleaner Shrimp, while Peach is a dental expert and a starfish.