Acanthurus polyzona

Acanthurus polyzona, commonly known as the black-barred surgeonfish^[3] or zebra tang,^[4] is a tropical fish found in coral reefs in the western Indian Ocean.^[5] It was first described in 1868 by the Dutch ichthyologistPieter Bleeker, who gave it the name Rhombotides polyzona; it was later transferred to the genus Acanthurus, becoming Acanthurus polyzona.^[2]

Acanthurus polyzona is a laterally flattened fish, roughly the shape of an almond, and can grow to a length of about 20 cm (8 in). 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.^[6]

The only fish with which it is likely to be confused is the "convict tang" (Acanthurus triostegus); 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.^[6]

Acanthurus polyzona has a rather restricted distribution in the tropical western Indian Ocean, its range including Madagascar, Mauritius, Réunion and the Comoro Islands. It lives in shallow reef habitats,^[5] in lagoons and on outer reef slopes, over sandy, rocky or coral seabeds at depths down to about 15 m (50 ft).^[6]

El pez cirujano cebra es diurno y se alimenta de algas, especialmente filamentosas . A menudo se asocia con cardúmenes de peces cirujano convictos, aprovechando la protección que les brinda el grupo. ^{[ 6 ]} Los juveniles, que son similares a los adultos en sus marcas pero algo más alargados, se asocian con peces cirujano convictos jóvenes. No se ha estudiado la reproducción de este pez; sin embargo, la tasa de crecimiento de los peces jóvenes es rápida, por lo que una población puede duplicarse en tan solo 15 meses. ^{[ 6 ]}