Chaetodon mertensii

Description

Chaetodon mertensii, the atoll butterflyfish, yellowback butterflyfish or Merten's butterflyfish, is a species of butterflyfish (family Chaetodontidae). It is found in the Pacific Ocean from the Ryukyu Islands to the Philippines and extending to Lord Howe Island, Rapa Iti and the Tuamotus. It grows to a maximum of 12.5 cm (5 in) long. Body color is white with 5-7 chevron-shaped dark grey bands on the sides. The posterior portion of the trunk, the adjacent dorsal and anal fins, and the posterior portion of the caudal fin are orange or yellow. A vertical black bar runs across the eye and over the nape without a break; in the similar species there is a separate nape spot and eyestripe. The atoll butterflyfish is found in deep lagoons and seaward reefs at 10–120 m depth. It feeds on algae and small benthic invertebrates.