Naso caeruleacauda

Bluetail unicornfish | Blue Unicornfish
Naso caeruleacauda
Naso caeruleacauda, Bali, Indonesia, Photo: Ian Shaw


Tropical Indo-Pacific


Brown oval-shaped body, blue tail with straight (or near-straight) rear margin, and pointed head profile in front of eye. Often with a white patch on tail base. N. hexacanthus (Sleek Unicornfish) has dark oblique bar on operculum, and N. caesius (Silverblotched Unicornfish) has more rounded head profile in front of eye.


Max Size: 40 cm

Sea Temperature Range: 24.4-30.4°C

Depth: 5-40m

Habitat Generalization Index: N/A

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 (2.2% 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 (86 per transect)

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

Edit by: Joe Shields