Sub-adult. Photo. (c) 2023 John Nevill.
Sub-adult. Photo. (c) 2023 John Nevill.
Sub-adult. Photo. (c) 2023 John Nevill.
Scientific Name: Naso annulatus
English Name: Whitemargin unicornfish
Creole Name: Korn
French Name: Nason à rostre long
IUCN Red List Status: Least Concern (LC)
Description:
Dorsal spines: 5; Dorsal rays: 28-29; Anal spines: 2; Anal rays: 27-28.
Medium to large unicornfish. At approximately 20 cm TL a long horn begins to develop from a bump anterior to the eye.The horn of mature fish can be as
long as the head. Dorsal profile of snout to base of horn forming an angle of about 60° to the horizontal. Body tapers to a narrow caudal peduncle
exhibiting two scutes each bearing a strong keel. Caudal fin truncate in sub-adults, scalloped in adults, the large males with a long trailing filament
from each corner.
Colour. Base colour light blusih grey to brown paler ventrally. No dark markings on head or body. Lips white. Juveniles and sub-adults with
a white ring around caudal peduncle and a white posterior edge on the caudal fin. Sub-adults develop a dark submarginal zone on caudal fin. Caudal fin
membranes white.
Size:
Maturity: Unknown. Max length : 100.0 cm TL.
Habitat and Ecology:
Reef associated species (depth 1-60 m, usually 25-60 m). Juveniles can be found on reefs around shallow lagoons. Adults are rarely seen at depths of less
than 25 m, typically found on steep drop-offs usually in small aggregations. Benthopelagic. Feeds on green filamentous algae as juveniles and gelatinous zooplankton as
adults. Feeds during the day and shelters within reef during the night.
Fishery Status:
This species is not protected or subject to fishery regulations. It is caught in the trap fishery, adults are likely subject to the handline fishery.
Notes:
Photo. shows a sub-adult caught in fish trap east coast Mahe, October 2023.
References:
Abesamis, R. et al. (2012). Naso annulatus. The IUCN Red List 2012: https://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T177988A1512439.en. (09/11/23).
Froese, R. & D. Pauly. Eds. (2023). FishBase. Naso annulatus. https://fishbase.mnhn.fr/summary/Naso-annulatus.html (09/11/23).
McGrouther, M. (2022). Ringtail Unicornfish, Naso annulatus. https://australian.museum/learn/animals/fishes/ringtail-unicornfish-naso-annulatus/ (09/11/23).
Randall, J.E. (2001). Surgeonfishes of Hawaii and the World. ISBN: 1-56647-561-9.
Citation:
Nevill, J.E.G. (2023). Naso annulatus, Whitemargin unicornfish. Seychelles Seatizens. www.seatizens.sc. https://seatizens.sc/species/naso-annulatus-quoy-gaimard-1825/