The yellowback fusilier (''Caesio xanthonota'') is a

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

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 fusilier 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 ...

Caesionidae. It is native to the tropical Indo-Pacific, being found in shallow water from the East African coast to Indonesia.

Taxonomy

The yellowback fusilier was first formally described in 1853 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 ...

Pieter Bleeker Pieter Bleeker (10 July 1819 – 24 January 1878) was a Dutch medical doctor, Ichthyology, ichthyologist, and Herpetology, herpetologist. He was famous for the ''Atlas Ichthyologique des Indes Orientales Néêrlandaises'', his monumental work on ...

with the type locality given as Batavia on

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 ...

. This species has been placed in the

subgenus In biology, a subgenus ( 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 the ge ...

''Flavicaesio''. The specific name ''xanthonota'' is a compunction of ''xantho'' meaning "yellow" and ''nota'' meaning "back", a reference to the yellow upperparts of this species.

Description

The yellowback fusilier is a small to medium-sized

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

which grows to about long. The mouth is small and terminal and is protusible, being able to be extended forward to swallow food. The body is fusiform or spindle-shaped. The dorsal fin has 10 spines and 14–15 soft rays. The anal fin has three spines and 11 or 12 soft rays. 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 ...

is deeply forked. The body coloration is greyish blue with a bright yellow zone on the back. The yellow area goes from the forehead, between the eyes, to the tail, and includes 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 ...

and the

. This area corresponds more or less to the upper third of the body. The belly is plain white.

Distribution and habitat

''Caesio xanthonota'' is widely distributed throughout the

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 ...

waters of the

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), ...

, the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

and

Persian Gulf The Persian Gulf, sometimes called the Arabian Gulf, is a Mediterranean seas, mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula.Un ...

excluded, to Indonesia in 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 ...

. It lives in mid-water in deep lagoons and close to external reefs from the surfaceto 50 m deep.

Diet

It feeds 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 ...

, so it is a

planktivore A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and i ...

.Lieske & Myers,''Coral reef fishes'', Princeton University Press, 2009,

Behaviour

The yellowback fusilier is diurnal, and lives in groups and forms schools with other caesionids such as ''

Caesio teres ''Caesio teres'', the yellow and blueback fusilier, beautiful fusilier, blue and gold fusilier (not to be confused with Caesio caerulaurea) or yellow-tail fusilier, is a species of Marine habitats, marine, pelagic ray-finned fish belonging to the ...

''.

References

External links

*http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=550964 {{Taxonbar, from=Q1021931 Yellowback fusilier Fish described in 1853