Indian Redfin Butterflyfish (juvenile)

Chaetodon trifasciatus is a species of butterflyfish (family Chaetodontidae).

Description

A pale orange butterflyfish with a bluish rear section, with oblique purplish stripes along sides, a yellow-margined black band through the eye and along the dorsal and anal-fin bases, a reddish-orange anal fin and a yellowish-orange caudal peduncle.

The Oval Butterflyfish (C. lunulatus) and the Black-tailed Butterflyfish (C. austriacus) resemble C. trifasciatus in coloration. The former has a less conspicuous back patch below the dorsal fin and a mainly dark anal fin, while the latter has black caudal and anal fins.

Distribution

The Melon Butterflyfish is found in the Indian Ocean from East Africa to the Raja Ampat Islands, West Papua, Indonesia, and the Australian territories of Cocos (Keeling) Islands and Christmas Island.

Habitat

Found at depths between 2 and 20 m, in coral-rich lagoons and semi-protected seaward reefs. Small juveniles are secretive and hide in corals.

Ecology and behaviour

Growing to a maximum of 15 cm long, the monogamous adults swim in pairs and may be territorial and aggressive to other Chaetodon. Melon Butterflyfish feed exclusively on coral polyps, particularly of Pocillopora. They are oviparous.

Biology

This is one species of a closely related group which includes the Black-tailed Butterflyfish (C. austriacus) of the Red Sea and Gulf of Aden and the Oval Butterflyfish (C. lunulatus) which is found in the western Pacific, from eastern coasts of the Indonesian islands to Australia.

Melon, Black-tailed and Oval butterflyfishes and probably also the somewhat aberrant Arabian Butterflyfish (C. melapterus) make up the subgenus Corallochaetodon, of which C. trifasciatus is the type species. They are probably quite close to the subgenus called "Citharoedus" (that name is a junior homonym of a mollusc genus), which contains for example the Scrawled Butterflyfish (C. meyeri). Like that group, they might be separated in Megaprotodon if the genus Chaetodon is split up.