The moorish idol (Zanclus cornutus) is one of the most memorable fish on a Hawaiian reef. They are commonly seen grazing along the open reef in shallow water. I often find these fish in caves as well, which seems quite odd as few daytime fish venture into the dark. The sponge and algae covered walls apparently provide good grazing.
![Moorish Idol](http://darkerview.com/wordpress/wp-content/uploads/2013/02/CF28-72-13055-DC.jpg)