The Triangular Butterflyfish (Chaetodon baronessa) is a member of the ‘Butterflyfishes’ family Chaetodontidae. It is a tropical fish species that can be found in the warm regions of the western Pacific. It is known to occur from the Cocos-Keeling Islands in the eastern Indian Ocean to Fiji and Tonja in the Pacific, north to the waters of southern Japan and south to New Caledonia, the Great Barrier Reef and the waters of northern New South Wales in Australia. A very similar species Chaetodon triangulum can be found in the waters of the Indian Ocean. This species has an unusual pattern on its body with alternating cream and grey-brown to purplish chevron-shaped narrow bars covering each side. Across the head there are three dark bars (with a single bar running through the eye) and the snout is generally coloured pink. It can be found living on coral reefs and in lagoons and it generally seen in pairs and is also considered to be territorial. It is known to feed exclusively on the polyps of the tubular Acropora corals. The Triangular Butterflyfish (Chaetodon baronessa) grows to a maximum length of approximately 15cm.