Marquesas butterflyfish

The Marquesas butterflyfish is an attractive species with a silvery-white body marked with black spots and having the upper posterior part of the body with a blackish wedge shaped area. There is also a yellow vertical band running through the eye. The dorsal fin is yellowish-orange while the caudal fin is yellow.[2] They are known to reach a total length of 12 centimetres (4.7 in).[3]

The Marquesas butterflyfish is restricted to the Central Pacific Ocean, where it is confined to the Line Islands in the United States Minor Outlying Islands, Phoenix Islands in French Polynesia and Kiribati and Marquesas in French Polynesia.[1]

The Marquesas butterflyfish occurs over rocky and sandy bottoms and is an oviparous species which forms pairs for breeding.[3] It is found at depths of between 20 and 80 metres (66 and 262 ft).[1] In the wild this omnivorous species feeds on coral polyps, fanworms, crustaceans, tunicates and algae.[2]

The Marquesas butterflyfish was first formally described in 1975 by the American ichthyologist John Ernest Randall with the type locality given as Hanauu Bay on Fatu Hiva in the Marquesas Islands.[4] The specific name declivis is Latin for sloping and refers to the diagonally sloping dark patch on the upper posterior part of the body and fins.[5] Populations of similar fishes to C. declivis in the Marshall Islands are thought to be hybrids between this species and the Burgess' butterflyfish (C. burgessi).[6]

The Marquesas butterflyfish was formerly caught in numbers for the aquarium trade but this has declined since 2006.[1]