The black-backed butterflyfish or blackback butterflyfish (''Chaetodon melannotus'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

butterflyfish The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. The approximately 129 species in 12 genera are found mostly on the reefs of the Atla ...

(

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Chaetodontidae). It is widespread through the Indo-Pacific area from the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

and East Africa to

Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...

, to southern Japan and throughout

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...

. This fish grows up to 18 cm (ca. 7 in) long, and may live for up to 20 years. When observed at night or when frightened, this species changes color; the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

portion of the body turns black except for two white patches. It belongs to the large subgenus ''Rabdophorus'' which might warrant recognition as a distinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

. In this group, it appears a close relative of the spot-tailed butterflyfish (''C. ocellicaudus'') and somewhat less close to the yellow-dotted butterflyfish (''C. selene''). These are all of oval shape, silvery with yellow fins and snout, ascending diagonal stripes, and black markings around the eyes, on the

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

, and sometimes on the back. Next closest seem the

saddle butterflyfish The saddle butterflyfish (''Chaetodon ephippium'') is a species of marine ray-finned fish, a butterflyfish belonging to the family Chaetodontidae. It is found in the Indian and Pacific Oceans from Sri Lanka and the Cocos-Keeling Islands to the ...

(''C. ephippium'') and the dotted butterflyfish (''C. semeion''), but these are already so distant that their ancestors must have diverged from those soon after the ''Rabdophorus'' lineage started to diversify. These oviparous fish are common on staghorn coral thickets, they are less seen on exposed parts of

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock o ...

s. Black-backed butterflyfish are generally found between 4 and 20 m deep, usually solitary, in pairs during the breeding season. Juveniles are more commonly found inshore, in pairs or traveling in small groups. It feeds primarily on the polyps of soft and hard

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...

s. The Black-backed Butterflyfish is easy to maintain in the aquarium by the standards of its

References

External links

* {{Taxonbar, from=Q2717383 Chaetodon Fish of the Red Sea