Photo copyright Tim Nicholson.
Taken in the Egyptian Red Sea.
Crown Butterflyfish, Chaetodon paucifasciatus (Ahl)

Can be seen between 4 and 30 m in pairs or groups. Not shown in the photo is its distinctive red rear. It's key identification feature, though, is the yellow stripe through the eye. The Crown Butterfly fish feeds on coral polyps, algae and crustaceans. It is only found in the Red Sea and the Gulf of Aden.

The Butterfly fish family or Chaetodontidae are small, colourful fishes with a continuous dorsal fin. Chaetodontidae means Greek bristle teeth and indeed they do have small, brush-like teeth. Most species are active during the day, resting among corals or rocks at night. Some species feed on coral polyps, and these tend to be territorial. When part of a coral is attacked in this way, the surrounding polyps often withdraw as far as they can into their protective skeletons. The fish then has to move further along the reef.

Most species of butterfly fish patrol a home range. Many species are heterosexual pairs that may remain together for years, if not life.

Further Reading:
Coral Reef Fishes, Indo-Pacific and Caribbean , Ewald Lieske and Robert Myers
Underwater Photographer , Martin Edge
The Red Sea in Egypt Part 1, Farid S Atiya