Naso tonganus

Humpnose Unicornfish | Bluntnose Unicornfish | Bulbnose Unicornfish | Humphead Unicornfish
Naso tonganus
Naso tonganus, Great Barrier Reef, Cairns, QLD, Photo: Andrew Green
Naso tonganus
Naso tonganus, Coral Sea, QLD, Photo: Andrew Green
Naso tonganus
Naso tonganus, Coral Sea, Australia, Photo: Ian Shaw
Naso tonganus
Naso tonganus, juvenile, NSW, Australia, Photo: Tom Davis
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Naso tonganus
Naso tonganus
Naso tonganus
Naso tonganus


Tropical Indo-Pacific


Heavy silver-grey body with humpbacked appearance, large rounded hump-like protuberance on snout, dark oblique lines on face and dark rear margins on pectoral and tail fins. Similar species in the western Indian Ocean, the Naso tuberosus (Humpnose Unicornfish), has a large dark patch on chest.


Max Size: 60 cm

Sea Temperature Range: 22-29.5°C

Depth: 2-40m

Habitat Generalization Index: 14.71

Also referred to as the SGI (Species Generalisation Index), this describes the habitat niche breadth of the species. Species with values less than 15 are found in a relatively narrow range of reef habitat types (specialists), while those over 25 may be found on most hard substrates within their range (generalists). Learn more here.

Conservation and Rarity

IUCN Status: Least Concern

Occurrence: Common (20.7% of sites)

Occurrence describes how often the species is found on surveys within its distribution. It is calculated as the % of reef sites surveyed by RLS divers across all the ecoregions in which the species has been observed

Abundance: Several (6 per transect)

Abundance is calculated as the average number of individuals recorded per RLS transect, where present.

Edit by: Joe Shields