Heniochus diphreutes, commonly known as the Long-fin Bannerfish, occurs in the Indo-Pacific, from East Africa and the Persian Gulf to the Society Islands, north to southern Japan, south to Lord Howe Island. It has also been observed in New South Wales, Western Australia, and New Guinea (Steene, 1977).

Biogeographic Regions: indian ocean (Native ); pacific ocean (Native )

This fish is recognized by its elongated dorsal spine and the bony protuberance on the forehead, differentiating it from other butterflyfish. This coral dwelling fish is laterally flattened and oval in shape. Most juvenile coloration and characteristics are retained in the adult, but the dorsal spine length increases as the fish matures (Steene, 1977). Heniochus diphreutes has a white body with two broad black bands running vertically behind the eye. Soft yellow dorsal and caudal fins are also characteristic features. They have a long snout/jaws, and bristlelike teeth allowing them to reach their main food source present in crevices in coral reefs. These fish grow to be between approximately 15-20 cm in length (Bailey, 1998).

Butterflyfish have a specific larval stage, called the tholilicthys stage. It is characterized by head bones that are expanded, covering the larvae in bony plates. These larvae can remain for several weeks to several months, and are planktonic.

• Marine

Butterflyfishes live in tropical marine waters. They associate with coral reefs and sheltered coastal bays. These fish tend to inhabit deep protected lagoons and channels, and deeper parts of reef slopes, between 30°S and 35°N (Eli, 2000).

Aquatic Biomes: reef ; coastal

Long-fin Bannerfish are coral reef feeders, feeding on both coral and small invertebrates living in the reefs (Steene, 1977). As aquarium fishes they eat a variety of foods including flakes, and pellets (Bailey, 1998). Juveniles sometimes eat parasites off of other fish.

Not much is known about reproduction in this species. However, they do produce small buoyant eggs that float to the surface after they are released. Hatching time ranges from 18-30 hours at about 29 degrees Celsius. The larvae then remains planktonic, with expanded bony plates (see Physical Characteristics) for an amount of time ranging from few weeks to few months (Paxton, 1994).

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

None

Heniochus diphreutes is a very beautiful and popular fish that is fairly easy to care for, and thus is sold commercially (Bailey,1998).