''Parachaetodon'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

butterflyfish The butterflyfish are a group of conspicuous tropical ocean, 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 ...

es, the only species being the sixspine butterflyfish (''Parachaetodon ocellatus''), which is also known as the ocellate butterflyfish or eyespot butterflyfish. is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

native to

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

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 component, abiotic (non-living) processes such as deposition (geol ...

s of the eastern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

and the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

Description

''Parachaetodon ocellatus'' has a largely yellow, triangular

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

. The background colour of the body is white and there are five brow or orange bands. The first of these runs through the eye and is orange in colour edged with black. The band that starts underneath the centre of the dorsal fin has a dark blotch near the base of the fin. Another, oval shaped black mark with a silvery forward margin is located on the caudal peduncle. There is a fainter bar along the margins of the dorsal and

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

s. The dorsal fin contains 6-7 spines and 28-30 soft rays while the anal fin has 3 spines and 18-20 soft rays. This species attains a maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

of .

Distribution

''Parachaetodon ocellatus'' has an Indo-Pacific distribution which extends from eastern India and Sri Lanka east through the south-east Asia, Indonesia and the Philippines and into the Pacific Ocean as far as the Fiji. It reach as far north as the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Geography of Taiwan, Taiwan: the Ryukyu Islands are divided into the Satsunan Islands (Ōsumi Islands, Ōsumi, Tokara Islands, Tokara and A ...

and

Ogasawara Islands The Bonin Islands, also known as the , is a Japanese archipelago of over 30 subtropical and tropical islands located around SSE of Tokyo and northwest of Guam. The group as a whole has a total area of but only two of the islands are permanen ...

of Japan and south to Australia. in Australia it ranges from the

Houtman Abrolhos The Houtman Abrolhos (often called the Abrolhos Islands) is a chain of 122 islands and associated coral reefs in the Indian Ocean off the west coast of Australia about west of Geraldton, Western Australia. It is the southernmost true coral r ...

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

, although juveniles have been recorded as far south as

Perth Perth () is the list of Australian capital cities, capital city of Western Australia. It is the list of cities in Australia by population, fourth-most-populous city in Australia, with a population of over 2.3 million within Greater Perth . The ...

, north around Australia’s tropical coast then as far south as

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

on the east coast.

Habitat and biology

''Parachaetodon ocellatus'' is found on coastal and inner reefs, typically as pairs or in small aggregations over open areas with a sand or silt substrate, These normally have scattered patches of

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

. Juveniles are occasionally recorded in seagrass in sheltered areas such as bays or lagoons. The diet consists of small benthic invertebrates and maybe some sponges. it is an

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

species forming pairs for

spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

Systematics

''Parachaetodon ocellatus'' was first formally described in 1831 as ''Platax ocellatus'' by the French

anatomist Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

Georges Cuvier (1768-1832). The Dutch ichthyologist Pieter Bleeker described a new species of butterflyfish, ''Chaetodon oligacanthus'', from

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

in 1850. In 1874 Bleeker placed ''C. ocellatus'' in the new genus ''Parachaetodon''. This was considered by later workers to be closely related or

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with Cuvier’s ''Platax ocellatus''.

References

Chaetodontidae Marine fish genera Taxa named by Pieter Bleeker Monotypic fish genera {{Chaetodontidae-stub