The schooling bannerfish (Heniochus diphreutes), also known as the false moorish idol, is a marine ray-finned fish, a butterflyfish from the family Chaetodontidae.
[2][3] Its body is compressed laterally, and the first rays of its dorsal fin stretch in a long white filament.
The schooling bannerfish is widespread throughout the tropical, subtropical and temperate waters of the Indo-Pacific from the eastern coast of Africa, Red Sea included, to Polynesia and Hawaii and from the Great barrier reef, to south Japan to the Kermadec Islands (New Zealand).
It feeds on zooplankton in the open water, and juveniles may act as cleaner fish,[2][3][5] and this has also been seen in adults.
[7] In some geographic areas, the schooling bannerfish is harvested for the aquarium trade and is commonly sold as a cheaper alternative to the Moorish idol.