The millet butterflyfish (''Chaetodon miliaris'') 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 Atlant ...

in the

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

Chaetodontidae. Other common names include the lemon butterflyfish and the millet-seed butterflyfish. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...

and the

Johnston Atoll Johnston Atoll is an Unincorporated territories of the United States, unincorporated territory of the United States, currently administered by the United States Fish and Wildlife Service (USFWS). Johnston Atoll is a National Wildlife Refuge and ...

, where it is found at depths down to . Although it has a limited range, it is common around Hawaii, and the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has listed its conservation status as being of "

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

Taxonomy

In its

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

''Exornator'', it probably belongs to a group that also includes the African butterflyfish (''C. dolosus''), the crochet butterflyfish ('' C. guentheri'') and the reef butterflyfish (''C. sedentarius''). The crochet butterflyfish might be the closest living relative of ''C. miliaris''. If the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 migh ...

'' is split up, ''Exornator'' might become a subgenus of ''Lepidochaetodon''.

Description

The millet butterflyfish grows to a maximum length of . It is a deep-bodied, laterally flattened fish. The dorsal fin has 13 to 14 spines and 20 to 23 soft rays and the anal fin has 2 to 3 spines and 17 to 20 soft rays. The general body colour is whitish or yellow, with a number of vertical rows of dark spots on the flanks. A broad black stripe runs from above the eye to the base of the operculum, and there is a large black patch on the caudal peduncle.

Distribution and habitat

This fish is endemic to the

and the

, and is found down to depths of at least . Its habitats include coastal fringing reefs, outer reefs and lagoons.

Ecology

The millet butterflyfish is a schooling species found in mid-water that feeds on

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. It also feeds opportunistically on

polychaete worms Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

and other small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s on the seabed. Food is drawn into the mouth by rapid suction. It does not seem to be

territorial A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

but forms aggregations to feed at particular sites on the reef. Although its breeding habits are unknown, the gonads are large as compared with the body size, suggesting that it may have a promiscuous mating system. Breeding takes place between January and May, and newly settled juveniles are found in inner reef areas between April and June. This butterflyfish is sometimes collected from the wild for the aquarium trade. Its feeding habits make it more suitable for keeping in a reef aquarium than more specialist butterflyfish species that feed on

scleractinia Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyp (zoology), polyps and have a cylindrical body crowned by an oral di ...

n corals. Although rare at Johnston Atoll, it is plentiful around the Hawaiian Islands. The

believes that the population is stable and that collection has little impact, and they assess the conservation status of this fish as being of "

References

{{Taxonbar, from=Q206360 Chaetodon Endemic fauna of Hawaii Fish of Hawaii Fish described in 1825