Naso annulatusRingtail Unicornfish | Long-horn Unicornfish | Nosefish | Whitemargin Unicornfish
Temperate Australasia, Tropical Indo-Pacific
Blue-grey body with long tapering horn on forehead projecting well forward of mouth. Tail brown with white radiating markings at rear, trailing filamentous tips on large male, and two tail spines. Juveniles grey with white patch on tail base. Lacks the convex tail shape and the lines on the face and body of N. brevirostris (Spotted Unicornfish).
Max Size: 100 cm
Sea Temperature Range: 24-31.4°C
Habitat Generalization Index: 1.94
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 (2.9% 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: Andrew Green