Naso caesius

Silverblotched Unicornfish | Gray Unicornfish
Naso caesius
Naso caesius, Cook Islands, Photo: Graham Edgar
Naso caesius
Naso caesius, Coral Sea, Australia, Photo: Rick Stuart-Smith
1 / 2
Naso caesius
Naso caesius



Dark grey-brown oval-shaped body, occasionally with dark streak blotches on side, dark tail with a straight rear margin, and two tail spines. Head profile more rounded in front of eye than in N. caeruleacauda (Blue Unicornfish), and lacks oblique dark bar on gill cover of N. hexacanthus (Sleek Unicornfish).


Max Size: 46 cm

Sea Temperature Range: 22.4-31.3°C

Depth: 3-50m

Habitat Generalization Index: 8.81

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: Infrequent (9.1% 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: Many (10 per transect)

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

Edit by: Joe Shields