Chaetodon melannotus Bloch & Schneider, 1801

Common Names and Taxonomic Family

The black-backed butterflyfish (also called blackback butterflyfish, Chaetodon melannotus) is a species of butterflyfish belonging to the family Chaetodontidae.

Geographic Distribution

It has a wide distribution across the Indo-Pacific, ranging from the Red Sea and East Africa to Samoa, southern Japan, and all of Micronesia.

Size and Lifespan

This species can grow up to 18 centimeters (about 7 inches) in length, and may reach a lifespan of up to 20 years.

Color Change Response

When seen at night or when frightened, the fish changes color: the dorsal section of its body turns black, with the exception of two white patches.

Subgenus Classification

It is classified in the large subgenus Rabdophorus, which some consider deserving of recognition as a separate genus.

Closest Related Species

Within this group, it is a close relative of the spot-tailed butterflyfish (C. ocellicaudus), and more distantly related to the yellow-dotted butterflyfish (C. selene).

Shared Morphological Traits

All three of these species have an oval body shape, silvery base coloration with yellow fins and snout, ascending diagonal stripes, and black markings around the eyes, on the caudal peduncle, and sometimes on the back.

Divergent Relatives

The next closest relatives are the saddle butterflyfish (C. ephippium) and the dotted butterflyfish (C. semeion), but these lineages diverged very early, soon after the Rabdophorus lineage began diversifying.

Habitat Preferences

This oviparous fish is common in staghorn coral thickets, and is encountered less often on exposed sections of reefs.

Depth Range

Black-backed butterflyfish are typically found at depths between 4 and 20 meters.

Adult Social Behavior

They are usually solitary, but form pairs during the breeding season.

Juvenile Behavior and Habitat

Juveniles are most often found inshore, occurring in pairs or moving in small groups.

Diet

Their diet consists primarily of polyps from both soft and hard corals.

Aquarium Suitability

By the general care standards for its genus, the black-backed butterflyfish is easy to keep in home aquariums.