It grows to a maximum of 16 cm long.The body has a pattern of alternating cream and grey-brown to purple chevron-shaped bars. There are three dark bars on the head, including one running across the eye.[2]
The eastern triangle butterflyfish is found in seaward and lagooncoral reefs. They usually swim around in pairs and are territorial. This species feeds exclusively on the polyps of the tubular Acropora corals.[2]
The triangle butterflyfish (C. triangulum) is its western sister species, replacing C. baronessa in the Indian Ocean. The triangle butterflyfishes and the hooded butterflyfish (C. larvatus) form the subgenusGonochaetodon. If Chaetodon is split up as some researchers propose, this group might go into Megaprotodon as other high-backed and square-bodied species, but its exact relationships are still not well known.[4][5]
^Fessler, Jennifer L.; Westneat, Mark W (2007). "Molecular phylogenetics of the butterflyfishes (Chaetodontidae): Taxonomy and biogeography of a global coral reef fish family". Molecular Phylogenetics and Evolution. 45 (1): 50–68. Bibcode:2007MolPE..45...50F. doi:10.1016/j.ympev.2007.05.018. PMID17625921.
