Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Acanthuridae

Scientific Name: Naso caeruleacauda
Species Authority: Randall, 1994
Common Name(s):
English Bluetail Unicornfish

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2010-05-04
Assessor(s): Russell, B., Choat, J.H., Abesamis, R., Clements, K.D., McIlwain, J., Myers, R., Nanola, C., Rocha, L.A. & Stockwell, B.
Reviewer(s): Edgar, G. & Kulbicki, M.
Naso caeruleacauda is widely distributed in the Coral Triangle Region. It occurs in moderately deep water. It is caught only incidentally in subsistence fisheries and there is no evidence of declines from harvesting. It is found in a number of marine reserves in the Coral Triangle. It is therefore listed as Least Concern.

Geographic Range [top]

Range Description: Naso caeruleacauda is found from the Philippines, Indonesia and the northern Great Barrier Reef, Australia. It was also recorded from northwest Madagascar (Allen 2005).
Countries occurrence:
Australia; Indonesia; Madagascar; Malaysia; Papua New Guinea; Philippines; Timor-Leste
FAO Marine Fishing Areas:
Indian Ocean – eastern; Indian Ocean – western; Pacific – western central
Lower depth limit (metres): 40
Upper depth limit (metres): 5
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Naso caeruleocauda was recorded as occasional in terms of relative abundance in the northern Bismarck Sea, Papua New Guinea and in Raja Ampat, Indonesia (Allen 2009, 2003b). It is occasional in the Philippines (R. Abesamis, C. Nanola and B. Stockwell pers. comm. 2010). There was only one school recorded from northwest Madagascar (Allen 2005).
Current Population Trend: Stable
Additional data:
Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: Naso caeruleacauda forms aggregations off seaward slopes, generally at depths greater than 15 m where it feeds on zooplankton. It sometimes swims in mixed schools with Naso hexacanthus.


The sexes are separate among the acanthurids. In Papua New Guinea, it is known to form spawning aggregations in open water above the reef every month of the year during the first and third quarter moon phase. It was reported to spawn early morning and late afternoon with group and pair spawning observed. N. caeruleacauda and N. caesisus are reported to aggregate bimonthly, just prior to the new and full moons. Several hundred species were observed to spawn  (Hamilton et al. 2004).
Systems: Marine

Use and Trade [top]

Use and Trade: Naso caeruleacauda is occasionally seen in fish markets. In a spawning aggregation site in Papua New Guinea, fishers interviewed state that catch rates have not changed in the years that they have targeted it. It was first exploited in 1999 (Hamilton et al. 2004). It is incidentally caught by gill nets in the Philippines.

Threats [top]

Major Threat(s): There are no major threats known for this species.

Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation measures in place for this species. However, its distribution overlaps several marine protected areas within its range.

Classifications [top]

9. Marine Neritic -> 9.8. Marine Neritic - Coral Reef -> 9.8.1. Outer Reef Channel
suitability: Suitable  
9. Marine Neritic -> 9.8. Marine Neritic - Coral Reef -> 9.8.3. Foreslope (Outer Reef Slope)
suitability: Suitable  

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
  Conservation sites identified:Yes, over part of range
  Occur in at least one PA:Yes
In-Place Species Management
In-Place Education
1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology
3. Monitoring -> 3.1. Population trends
3. Monitoring -> 3.2. Harvest level trends

♦  Food - human
 Local : ✓ 

Bibliography [top]

Allen, G.R. 2003b. Appendix 1. List of the Reef Fishes of the Raja Ampat Islands. In: R. Donnelly, D. Neville and P.J. Mous (eds), Report on a rapid ecological assessment of the Raja Ampat Islands, Papua, Eastern Indonesia, held October 30 – November 22, 2002. The Nature Conservancy - Southeast Asia Center for Marine Protected Areas, Sanur, Bali.

Allen, G.R. 2005. Fishes of northwest Madagascar. In: S.A. McKenna and G.R. Allen (eds), A Rapid Marine Biodiversity Assessment of the Coral Reefs of Northwest Madagascar, pp. 124. Conservation International, Washington, D.C.

Allen, G.R. 2009. Coral Reef Fish Diversity. In: R. Hamilton, A. Green and J. Almany (eds), Rapid Ecological Assessment: Northern Bismarck Sea, Papua New Guinea. Technical Report of survey conducted August 13 to September 7, 2006, The Nature Conservancy.

Comeros-Raynal, M.T., Choat, J.H., Polidoro, B., Clements, K.D., Abesamis, R., Craig, M.T., Lazuardi, M.E., McIlwain, J., Muljadi, A., Myers, R.F., et al.. 2012. The likelihood of extinction of iconic and dominant components of coral reefs: the parrotfishes and surgeonfishes. PLoS ONE

Hamilton, R., Matawai, M. and Potuku, T. 2004. Spawning Aggregations of Coral Reef Fish in New Ireland and Manus Provinces, Papua New Guinea: Local Knowledge Field Survey Report. (UNRESTRICTED ACCESS VERSION). TNC Pacific Island Countries Report No. 4/04. Pacific Island Countries Coastal Marine Program, The Nature Conservancy.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.2). Available at: (Accessed: 17 October 2012).

Randall, J.E. 2001a. Surgeonfishes of the world. Mutual Publishing and Bishop Museum Press, Hawai'i, Honolulu, Hawaii.

Reeson, P.H. 1983. The biology, ecology and bionomics of the surgeonfishes, Acanthuridae. In: J.L. Munro (ed.), Caribbean coral reef fishery resources, pp. 178-190.

Citation: Russell, B., Choat, J.H., Abesamis, R., Clements, K.D., McIlwain, J., Myers, R., Nanola, C., Rocha, L.A. & Stockwell, B. 2012. Naso caeruleacauda. The IUCN Red List of Threatened Species 2012: e.T177968A1505905. . Downloaded on 09 October 2015.
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