Desjardin's Sailfin Tang grows to a maximum length of 40 cm (16 in), with a sexual dimorphism, as males being larger than females. This species shows the typical morphology of the family Acanthuridae. The body is oval or disc-shaped, with erectile and much elevated dorsal and anal fins. In general, the upper side of the body alternates orange and dark blue vertical bands, with a larger blue band on the eyes, a spotted ventral region and numerous white spots on the head. The dorsal and anal fins have a pattern of horizontal alternate orange and blue bands. The caudal fin shows white spots and lines. Like most surgeonfish on each side of the caudal fin, in the middle of the caudal peduncle, there is a defensive dark spine surrounded by a blue zone. This spine is hinged and may unfolds to 80°.
Distinctive Characters: Dorsal fin with 4 spines and 27-31 rays. Anal fin with 3 spines and 22-24 rays. Pectoral rays 15-17. Body depth 1.8-2.0 in standard length. Dorsal and anal fins strongly elevated. No bristles on anterior to caudal spine.
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Adults usually can be found in pairs, while juveniles are solitary. When threatened, these fishes display their large ventral and dorsal fins. They feed primarily on filamentous algae, various macroalgae and plankton. However, individuals were regularly observed feeding on jellyfish (Scyphozoa) and comb jellies (Ctenophora) in the Red Sea. They are pair spawners, a typical trait of other fish in the Zebrasoma genus. This differs from the group spawning typical of the Acanthuridae family. Found in lagoon and seaward reefs to depths greater then 30 m; juveniles in sheltered inner reef areas. Adults usually occur in pairs. Juveniles solitary and commonly among staghorn corals in lagoons or protected reefs
Zebrasoma desjardini is widespread and occasionally to locally common in most parts of its range. It is harvested for the aquarium trade, but is not a major component. There are no major threats known and it occurs in a number of marine protected areas in parts of its distribution.
The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010).