About Chaetodon ocellicaudus Cuvier, 1831
Chaetodon ocellicaudus, commonly called the Spot-tailed Butterflyfish, is a species of marine ray-finned butterflyfish that belongs to the family Chaetodontidae. This species is distributed in the central Indo-west Pacific, ranging from Malaysia to New Guinea, and north to the Philippines and Palau in Micronesia. It reaches a maximum length of 15 cm (5.9 in).
It is nearly identical to the Black-backed Butterflyfish (C. melannotus), and only differs in the shape of the black marking on the caudal peduncle, the absence of a black marking on the chest, a lighter colored back, and an average of 14 pectoral fin rays instead of 15.
C. ocellicaudus is part of the large subgenus Rabdophorus, which may deserve recognition as a separate genus. Within this group, it is a close relative of the Black-backed Butterflyfish, and is less closely related to the Yellow-dotted Butterflyfish (C. selene). All three of these species have oval-shaped bodies, are silvery with yellow fins and snout, feature ascending diagonal stripes, and have black markings around the eyes, on the caudal peduncle, and sometimes on the back. The next closest relatives appear to be the Saddle Butterflyfish (C. ephippium) and the Dotted Butterflyfish (C. semeion), but these lineages are already distant enough that their ancestors diverged from the C. ocellicaudus lineage shortly after the Rabdophorus lineage began diversifying.
The Spot-tailed Butterflyfish inhabits coral reefs at depths between 3 and 15 meters. It occurs in coral-rich areas of reef flats, lagoons, and seaward reefs. Juveniles typically stay in inshore areas, while adults are usually found in pairs. This fish feeds on soft coral polyps, including Litophyton viridis and species from the genera Clavularia, Nephthia, and Sarcophyton.
