''Paracaesio xanthura'', the yellowtail blue snapper, the false fusilier, gold-backed fusilier, Pedley's fusilier or Southern fusilier, 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), ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, a snapper belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Lutjanidae Lutjanidae or snappers are a family of perciform fishes, mainly marine but with some members inhabiting estuaries and, in some cases, fresh water (e.g., '' Lutjanus goldiei''). The family includes about 113 species. Most species are used for foo ...

. It is native to the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region.

Description

''Paracaesio xanthura'' has a fusiform and moderately deep body. It has large eyes which are separated by a convex area, and a short snout which has a length equal to the diameter of the eye. The upper and lower jaws are roughly equal in length and are equipped with an outer row of canine-like teeth and an inner band of small bristle-like teeth. The

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 ...

has 10 spines and 10-11 soft rays while the anal fin has 3 spines and 8-9 soft rays. This species attains a maximum total length of . This species is bright blue with a vivid yellow band which runs along its back and extends onto the

caudal peduncle 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 only ...

and the

caudal 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 only ...

Distribution

''Paracaesio xanthura'' has a wide Indo-Pacific distribution. It is found from Kenya to South Africa on the coast of eastern Africa through the Indian Ocean, including Madagascar,

Comoros Islands The Comoro Islands are a group of volcanic islands in the Mozambique Channel, an arm of the Indian Ocean lying between Madagascar and the African mainland. Three of the islands form the Union of the Comoros, a sovereign nation, while Mayotte be ...

, Seychelles, Mauritius and

Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...

as well as the

Gulf of Aden The Gulf of Aden (; ) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, the Socotra Archipelago, Puntland in Somalia and Somaliland to the south. ...

, the Maldives and

Chagos Islands The Chagos Archipelago (, ) or Chagos Islands (formerly , and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about south of the Maldives archipelago. This chain of islands is the southernmo ...

, Sri Lanka and southern India. In the Pacific, it is found as far north as southern Japan, south to Australia and from the

Andaman Sea The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the northeastern Indian Ocean bounded by the coastlines of Myanmar and Thailand along the Gulf of Martaban and the west side of the Malay Peninsula, and separated f ...

in the west east to the

Austral Islands The Austral Islands ( officially ''Archipel des Australes;'' ) are the southernmost group of islands in French Polynesia, an overseas country of France, overseas country of the France, French Republic in the Oceania, South Pacific. Geographicall ...

. In Australia it is found on 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 ...

and the offshore reefs off northwestern

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 ...

, as well as the northern

Great Barrier Reef The Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

south to Montague Island in

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

and east to

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Port ...

in the

Tasman Sea The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 wa ...

Habitat and biology

''Paracaesio xanthura'' is associated with reefs and is found over rocky substrates where it occasionally forms large aggregations. It feeds mainly on

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and is found at depths between .

Systematics and etymology

''Paracaesio xanthura'' was first formally described in 1869 as ''Caseio xanthurus'' by the

Dutch Dutch or Nederlands commonly refers to: * Something of, from, or related to the Netherlands ** Dutch people as an ethnic group () ** Dutch nationality law, history and regulations of Dutch citizenship () ** Dutch language () * In specific terms, i ...

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

herpetologist Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

and

physician A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the Medical education, study, Med ...

Pieter Bleeker with the type locality given as Nosy-Bé off Madagascar. When Bleeker created the

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 ...

Paracaesio ''Paracaesio'' is a genus marine ray-finned fishes, snappers belonging to the Family (biology), family Lutjanidae. They are native to the Indian Ocean and the western Pacific Ocean, with these currently recognized species: * ''Paracaesio breviden ...

'' ''C. xanthoura'' was its only species and so was the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

monotypy 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 "unispe ...

, subsequently other species were added. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''xanthura'' means "yellow tail", a reference to the yellow caudal peduncle and tail.

Utilisation

''Paracaesio xanthura'' is considered to be a good food fish in some parts of its range and it is mostly taken using handlines and longlines. The catch is sold either fresh or frozen.

References

{{Taxonbar, from=Q2123949 xanthura Fish of the Indian Ocean Marine fish of South Africa Fish described in 1869