The emperor angelfish (''Pomacanthus imperator'') 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 angelfish. It is a

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 ...

-associated fish, native to the Indian and

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 ...

s, from 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 ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

and 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 ...

. This species is generally associated with stable populations and faces no major threats of extinction. It is a favorite of photographers, artists, and aquarists because of its unique, brilliant pattern of coloration.

Description

The emperor angelfish shows a marked difference between the juveniles and the adults. The juveniles have a dark blue body which is marked with concentric curving lines, alternating between pale blue and white with the smallest which are completely enclosed within each other located posteriorly. These lines become vertical at the anterior end. The dorsal fin has a white margin 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 ...

is transparent. The adults are striped with blue and yellow horizontal stripes, a light blue face with a dark blue mask over the eyes and a yellow caudal fin. There is a blackish band above the pectoral fins, the top of which is at the level of the upper orbit. The front margin of this band is bright blue and the rear margin is a thin yellow line. The anal fin has a dark blue background with lighter blue horizontal stripes. 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 13–14 spines and 17–21 soft rays while the

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 ...

has 3 spines and 18–21 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

The emperor angelfish has a wide

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 ...

distribution. It occurs from the Red Sea southwards along the East African coast to Mozambique and Madagascar, eastwards through the Indian and Pacific Oceans as far as the

Tuamotu Islands The Tuamotu Archipelago or the Tuamotu Islands (, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to ...

and the

Line Islands The Line Islands, Teraina Islands or Equatorial Islands () are a chain of 11 atolls (with partly or fully enclosed lagoons, except Vostok and Jarvis) and coral islands (with a surrounding reef) in the central Pacific Ocean, south of the Hawa ...

. It extends north to the Kansai region and to the southern regions of Japan and south to the

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, ...

of Australia,

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

and the

French Polynesia French Polynesia ( ; ; ) is an overseas collectivity of France and its sole #Governance, overseas country. It comprises 121 geographically dispersed islands and atolls stretching over more than in the Pacific Ocean, South Pacific Ocean. The t ...

. Vagrants have been recorded from

. It has been recorded at several sites off the coast of Florida and off Puerto Rico, and since 2009 as a recent introduction to the eastern Mediterranean basin where it now found in low numbers in a number of localities.

Habitat and biology

The emperor angelfish is found at depths between . The adults are found in areas where there is a rich growth of corals on clear lagoon, channel, or seaward reefs. Here they are normally observed underneath ledges and within caves. The subadults are frequently recorded in cavities in reefs and along surge channels on seaward reefs. The juveniles frequently shelter below ledges, in reef cavities and in relatively sheltered areas in channels and over outer reef flats. Its diet comprises

sponges 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 ar ...

and other encrusting organisms, as well as tunicates. They form pairs. The juveniles and adults may act as cleaner fish, cleaning ectoparasites off larger fishes. When frightened, these fish can produce a knocking sound.

Systematics

The emperor angelfish was first formally described in 1787 as ''Chaetodon imperator'' by the

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

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 ...

and

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

Marcus Elieser Bloch (1723–1799) with the type locality given as Japan. Some authorities place this species 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 ...

''Acanthochaetodon''. The specific name ''imperator'' means "emperor" and reflects the Dutch name ''Keyser van Iapan'' meaning "Emperor of Japan" coined by the publisher

Louis Renard Louis may refer to: People * Louis (given name), origin and several individuals with this name * Louis (surname) * Louis (singer), Serbian singer Other uses * Louis (coin), a French coin * HMS ''Louis'', two ships of the Royal Navy See also * ...

(ca. 1678–1746) in 1719, possibly reflecting its majestic appearance.

Utilisation

The emperor angelfish is common in the

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

trade.

Gallery

File:Pomacanthus imperator - Urocaridella sp. (38624510520).jpg, Emperor angelfish at

Wakatobi National Park Wakatobi National Park is a marine national park in Southeast Sulawesi, Indonesia. It was established in 2002. The name of Wakatobi is a portmanteau of the four main Tukangbesi Islands: Wangi-wangi, Kaledupa, Tomia, and Binongko. Since 2005 t ...

, 2018 File:Pomacanthidae Pomacanthus imperator 1.jpg, Emperor angelfish at Sea Life Bangkok Ocean World, 2007 File:Emperor angelfish (Pomacanthus imperator).jpg, Emperor angelfish at Raja Ampat, 2020 File:Emperor Angelfish, Western form - Pomacanthus imperator 1.jpg, Emperor angelfish at

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

France, 2013 File:Emperor angelfish (Pomacanthus imperator),.jpg, Adult Emperor angelfish,2012 File:Pomacanthus imperator (Emperor angelfish) juvenile Timor.jpg, Juvenile Emperor angelfish at

Manatuto Manatuto is a city in Manatuto Municipality, East Timor. Manatuto Vila has 3,692 inhabitants (Census 2015) and is capital of the subdistrict and district Manatuto. It is on the north coast of Timor, (about as the crow flies) east of Dili ...

Timor-Leste, 2006 File:Pomacanthus imperator (Emperor angelfish) juvenile.jpg, Juvenile Emperor angelfish at

Timor-Leste, 2006 File:Emperor Angelfish, juvenile - Pomacanthus imperator.jpg, Close up of Juvenile Emperor angelfish at

Marsa Alam Marsa Alam ( ' , Classical Arabic ) is a tourist List of cities and towns in Egypt, town in south-eastern Egypt, located on the western shore of the Red Sea. It is described as a "popular" tourist destination. Marsa Alam is a relatively recently ...

Egypt, 2014

References

External links

*Froese, R. and D. Pauly, Eds
''Pomacanthus imperator''.
FishBase. 2017. *Schofield, P. J
''Pomacanthus imperator''.
U.S. Geological Survey, Nonindigenous Aquatic Species Database.
Emperor Angelfish.
National Aquarium. * {{Taxonbar, from=Q847501 Pomacanthus Fish of Palau Fish described in 1787 Taxa named by Marcus Elieser Bloch