The Melon Butterflyfish (Chaetodon trifasciatus), is species of Butterflyfish (Family Chaetodontidae). It is found in the Indian from East Africa to Western Java. This is one species of a closely related group which includes the Black-tailed Butterflyfish(C. austriacus) of the Red Sea and Gulf and the Oval Butterflyfish (C. lunulatus) which is found in the western Pacific, from eastern coasts of the Indonesian islands to Australia.
The Oval Butterflyfish and the Black-tailed Butterflyfish 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.
The Melon Butterflyfish is 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. Growing to a maximum of 15cm 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