The bluelashed butterflyfish, Chaetodon bennetti, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of butterflyfish

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. Found mostly on the reefs of the Atlantic, Indian and Pacific Oceans, there are approximately 120 species in 10 genera...

 (family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Chaetodontidae). It is found in the Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

 from East Africa

East Africa

East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 to the Pitcairn Islands

Pitcairn Islands

The Pitcairn Islands , officially named the Pitcairn, Henderson, Ducie and Oeno Islands, form a group of four volcanic islands in the southern Pacific Ocean. The islands are a British Overseas Territory and overseas territory of the European Union in the Pacific...

, north to Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and south to Lord Howe Island

Lord Howe Island

Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...

 and Rapa Iti

Rapa Iti

Rapa or Rapa Iti as it is sometimes called in more recent years , is the largest and only inhabited island of the Bass Islands in French Polynesia. An older name for the island is Oparo Its area is 40 km2 with a population of almost 500 and a max elevation of 650 m...

.

It grows to a maximum of 20 cm (almost 8 in) long. The body is yellow with a black patch surrounded by a blue circle below the dorsal fin

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 and two curved blue lines above the belly. Its vertical black eyestripe is flanked by two blue lines.

Like the other butterflyfishes with angular yellow bodíes with black eyestripes and (except in the present species) a single differently-colored patch, it belongs in the subgenus

Subgenus

In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

 Tetrachaetodon. Among this group it seems to be the most basal living species. If Chaetodon

Chaetodon

Chaetodon is a tropical fish genus in the family Chaetodontidae. Like their relatives, they are known as "butterflyfish". This genus is by far the largest among the Chaetodontidae, with about 90 living species included here, though most might warrant recognition as distinct genera.Several subgenera...

is split up, this subgenus would be placed in Megaprotodon.

The bluelashed butterflyfish is found in seaward and lagoon

Lagoon

A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...

 reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s in areas with rich coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 growth. Juveniles may be found in shallow Acropora

Acropora

Acropora is a genus of scleractinian coral in the Phylum Cnidaria. Some of its species are known as table coral, elkhorn coral and staghorn coral. There are currently 149 described species...

thickets. Adults occur in pairs. This species feeds largely on coral polyps.