The Threadfin butterfly fish (Chaetodon Auriga) is common in Hawaii. It lives off of coral polyps, sponges, and invertebrates. Threadfin butterfly fish typically living in shallow waters, around 50 feet. They also are often seen in pairs. Threadfin Butterfly fish are territorial. They will drive any other types of Butterfly fish from their territory.
The Hawaiian name for this fish is Kīkākapu: the common name for many butterfly fish in the Hawaiian language.
How can you tell the difference between a butterfly fish and others? It’s quite easy: the vast majority of butterfly fish has the colors black, white, and  yellow. In addition to this, most of them have what is known as a “false eye spot.” This large and dark coloration on the tail side of the fish mimics a real eye and may confuse predators.
Images by Keoki Stender (http://www.marinelifephotography.com/)