About Chaetodon trifasciatus Park, 1797
Two other butterflyfish species, the oval butterflyfish and the blacktail butterflyfish, resemble Chaetodon trifasciatus in coloration. The oval butterflyfish has a less conspicuous patch on its back below the dorsal fin and a mostly dark anal fin, while the blacktail butterflyfish has black caudal and anal fins. C. trifasciatus, the melon butterflyfish, the blacktail butterflyfish, the oval butterflyfish, and likely the distinct Arabian butterflyfish (C. melapterus) form the subgenus Corallochaetodon, with C. trifasciatus as this subgenus's type species. This group is probably closely related to the subgenus currently referred to as "Citharoedus" — this name is a junior homonym of an existing mollusc genus — which includes species such as the scrawled butterflyfish (C. meyeri). If the genus Chaetodon is ever split into separate genera, both this group and Corallochaetodon would likely be separated into the genus Megaprotodon. The melon butterflyfish is distributed across the Indian Ocean, ranging from East Africa to Western Java. It inhabits coral-rich lagoons and semi-protected seaward reefs at depths between 2 and 20 meters. Small juvenile melon butterflyfish are secretive and hide within corals. This species reaches a maximum total length of 15 centimeters. Adult melon butterflyfish are monogamous, swim in pairs, and may be territorial and aggressive toward other Chaetodon butterflyfish. They feed exclusively on coral polyps, with a particular preference for those of the genus Pocillopora. This species is oviparous.
