Naso tonganus (Valenciennes, 1835)
Bulbnose unicornfish
photo by Randall, J.E.

Family:  Acanthuridae (Surgeonfishes, tangs, unicornfishes), subfamily: Nasinae
Max. size:  60 cm SL (male/unsexed)
Environment:  reef-associated; marine; depth range 2 - 40 m
Distribution:  Western Indian Ocean: Mauritius, Seychelles and Mozambique (probably wider distribution in this part of the ocean).
Diagnosis:  Dorsal spines (total): 5-5; Dorsal soft rays (total): 27-30; Anal spines: 2-2; Anal soft rays: 26-28. Description: Characterized by grey shading to yellowish grey on ventral parts; area below hump on back densely spotted with black; broad pale blue margin on blackish dorsal fin; caudal fin with broad submarginal blackish zone; large bulbous snout and hump on back; caudal peduncle with pair of bony plates, each with forward projecting point; greatest depth of body 2.2 (subadult)-3.0 in SL (Ref. 90102).
Biology:  Inhabits coral reefs (Ref. 37792). Feeds on leafy or fleshy algae and zooplankton (Ref. 37792). Found singly or in small groups (Ref. 37792).
IUCN Red List Status: Least Concern (LC); Date assessed: 06 May 2010 Ref. (130435)
Threat to humans:  harmless


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