Acanthuridae

Powder blue tang

Acanthurus leucosternon

Vast feeding crowds scour fine algae from narrow reef crevices

• Black
• Blue
• White
• Yellow
• Tropical
• Regional distribution
• Marine fish
• Compressed
• Medium
• Tropical fish

Sporting an electric sky-blue torso framed against an inky black facial mask, the powder blue tang is celebrated as one of the most stunning surgeonfishes of the tropical Indian Ocean. A pristine white throat patch separates the dark head from the vivid blue flank, while a radiant yellow dorsal fin and caudal peduncle provide dazzling visual contrast. Near the base of the tail lies a modified, razor-sharp modified scale known as the caudal spine or scalpel, encased in a conspicuous yellow protective sheath used defensively against rivals and predators. Found across the Indian Ocean from eastern Africa and Madagascar through the Maldives to the Andaman Sea and western Indonesia, it thrives on shallow wave-swept reef crests and upper seaward terraces down to twenty-five meters depth. Equipped with close-set spatulate teeth, it grazes voraciously on filamentous microalgae covering limestone rock. While solitary adults aggressively defend individual feeding territories, they frequently mass into roving feeding super-aggregations to overpower defensive damselfishes and graze unhindered. Maximum total length is recorded at twenty-three centimetres.

Sources: Florida Museum — Powder Blue Tang, Acanthurus leucosternon