''Acanthurus polyzona'', commonly known as the black-barred surgeonfish or zebra tang, is a tropical fish found in coral reefs in the western

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), ...

. It was first described in 1868 by the Dutch

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 ...

, who gave it the name ''Rhombotides polyzona''; it was later transferred to the genus ''

Acanthurus ''Acanthurus'' is a genus of marine ray-finned fish belonging to the family Acanthuridae, which includes the surgeonfishes, unicornfishes and tangs, found in the Atlantic, Indian and Pacific Ocean. They are found in tropical oceans, especially ...

'', becoming ''Acanthurus polyzona''.

Description

''Acanthurus polyzona'' is a laterally flattened fish, roughly the shape of an

almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...

, and can grow to a length of about . The head is short with a pointed snout and a terminal mouth with thick lips. The eyes are large and the two pairs of nostrils are immediately in front of the eyes. The overall colour of this fish is a very pale yellow, rather more olive-grey dorsally and more silvery-white ventrally. Superimposed on this pale background are nine broad black bands, narrowing slightly towards the belly; the first band passes through the eye, the second extends from the front of the dorsal fin to the base of the pectoral fins, and the eight and ninth bands are on the caudal peduncle. On either side of the peduncle is a small, retractable spine. The only fish with which it is likely to be confused is the "convict tang" (''

Acanthurus triostegus ''Acanthurus triostegus'', commonly known as convict tang, manini, convict surgeonfish, convict surgeon, or fiveband surgeonfish, is a species of marine ray-finned fish belonging to the Family (biology), family Acanthuridae which includes the ...

''); that species has a yellower background colour and just six vertical, rather more slender black bands. It is more widely distributed, and even within the zebra tang's restricted range, the convict tang is the common of the two.

Distribution

''Acanthurus polyzona'' has a rather restricted distribution in the tropical western Indian Ocean, its range including

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...

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 ...

and the

Comoro 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 bel ...

. It lives in shallow reef habitats, in lagoons and on outer reef slopes, over sandy, rocky or coral seabeds at depths down to about .

Ecology

The zebra tang is diurnal and feeds on algae, especially

filamentous algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

. It often associates with

shoals In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material, and rises from the bed of a body of water close to the surface or ...

of convict tangs, taking advantage of the protection given by numbers. The juveniles, which are similar to the adults in markings but rather more elongated, associate with young convict tangs. The reproduction of this fish has not been studied, however the growth rate of young fish is fast so that there may be a doubling of a population in as little as 15 months.

References

{{Taxonbar, from=Q1094671 polyzona Fish of the Indian Ocean Fish of the Comoros Fish of Madagascar Vertebrates of Réunion Vertebrates of Mauritius Fish described in 1868 Taxa named by Pieter Bleeker