IUCN Otter Specialist Group . . . leading global otter conservation Last Update: Sunday February 22, 2015
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Aonyx cinereus (Illiger, 1815), the Asian Small-Clawed Otter (currently being revised)




The smallest of the world's otters, about 0.9m long, weighing around 5kg. The most truly social otter, living in extended family groups around a breeding alpha pair. Group sizes of more than 20 animals have been recorded. These otters are extremely manually dextrous, using their forepaws to feel for mollusks and crustaceans in rocks, vegetation and mud. They are the least aquatic of all the otters.

This species used to be known as Amblonyx cinereus, and before that as Aonyx cinerea. DNA work by Koepfli & Wayne (1998 & 2003) indicated that the Asian Small-Clawed Otter is a sister species to the African Clawless and Congo Clawless Otters. Aonyx is the older name, so the Asian Small-Clawed Otter is now Aonyx cinereus.

CITES Identication Sheet


Small-Clawed Otters prefer shallow water, with a good food supply, and moderate to low bankside vegetation. They demonstrate a high climatic and trophic adaptability, occurring from tropical coastal wetlands up to mountain streams. They make use of freshwater and peat swamp forests, rice fields, lakes, streams, reservoirs, canals,drainage ditches, rice paddies, mangroves, tidal pools, and along the coastline. In mountainous areas, they frequent swift-flowing forest streams with rocks and boulders. Their preferred food is crustaceans and molluscs. Across much of their range they are sympatric with Eurasian Otters (Lutra lutra), Smooth-Coated Otters (Lutrogale perspicillata) and Hairy-Nosed Otters (Lutra sumatrana), and there is clear evidence of niche separation between the species.


Although the species' range appears large, in the last decade, actual distrubution has shrunk, especially in the west, compared to historical records. They are currently found from the Himalayan foothills of Himachal Pradesh eastward throughout south Asia, extending up to Philippines and down through Indonesia.. A small isolated subpopulation has been reported from southern Indian hill ranges of Coorg (Karnataka), Ashambu, Nilgiri and Palni hills (Tamil Nadu) and some places in Kerala. They were formerly found in Sri Lanka, but their current status there is unknown. The only areas in which these animals are today known to be common are Peninsular Malaysia, especially in Kedah, and in the western forests and southern marshes of Thailand.

Conservation Status

Red List Category VU (Vulnerable), population decreasing
Year Assessed 2015
Assessor Hussain, S.A. & de Silva, P.K.
Evaluators Conroy, J. (Otter Red List Authority) & Schipper, J. (Global Mammal Assessment Team4

Current Concerns

The main threat throughout Asian is habitat destruction because of deforestation (loss of the smaller hill streams), agriculture (especially tea and coffee plantations in India, draining of peat swamp forests, and destruction of coastal mangroves for aquaculture) and settlement. Water courses are being polluted with pesticides from planatations and other intensive agriculture, and heavy metals, affecting the gill-feeders on which this species depends, and interfering directly with otter physiology. Prey biomass is also being reduced by overexploitation, and the vast aquaculture industry regards otters as pests and persecutes them directly.

Although international and national level legal protection is in place, local legislation is needed. The impact of protection measures on livelihoods needs to be assessed and answered. Habitat protection and interpopulation corridors need to be established. Research on all aspects of this species biology and ecology is needed.

Leading Researchers

Source: Padma K de Silva, IUCN/SSC Asian coordinator

S.A. Hussain   India   Studies on the range and habitat utilization of small-clawed otter in South India.
Aadrean   Indonesia   Studies on diet, interactions with humans and threats including the pet trade in Indonesia

Key Publications


  • Harris, C.J. (1968). Otters: A Study of the Recent Lutrinae. Weidenfeld and Nicholson, London


  • Foster-Turley, P.A. (1992) Conservation Aspects of the Ecology of Asian Small-Clawed and Smooth Otters on the Malay Peninsulas IUCN Otter Spec. Group Bull. 7: 26 - 29
  • Foster-Turley, P.(1986). A Progress Report on the Species Survival Plan for Asian Small-Clawed Otters in United States Zoos. IUCN Otter Spec. Group Bull. 1: 19 - 21
  • Nugegoda, V. & Matthew, U. (1999). Reconditioning process of captive-bred oriental small-clawed otters prior to re-introduction to a mangrove habitat in Singapore. Re-introduction News 18: 20-21.

Captive Studies: Health

  • Borgwardt, N. & Culik, B.M. (1999). Asian Small-Clawed Otters (Amblonyx cinerea): Resting And Swimming Metabolic Rates. Journal of Comparative Physiology B 169: 100-106
  • Calle, P.P. & Robinson, P.T. (1985). Glucosuria Associated with Renal Calculi in Asian Small-Clawed Otters. Journal of the American Veterinary Association 187 (11): 1149-1153
  • Calle, P.P. (1988). Asian Small-Clawed Otter (Aonyx cinerea) Urolithiasis Prevalence in North America. Zoo Biology 7 (3): 233-242
  • Daengsvang, S. (1973). First Report on Gnathostoma vietnamicum Le-Van-Hoa 1965 from Urinary System of Otters (Aonyx cinereus, Illiger) in Thailand. Southeast Asian Journal of Tropical Medicine and Public Health 4 (1): 63-70
  • Dalton, L.M., Robeck, T.R. & Young, W.G. (1997). Squamous Cell Carcinoma On The Tongue Of An Asian Small-Clawed Otter (Amblonyx cinereus). IAAAM Proceedings 28: 136
  • Lewis, J.C.M. (1991). Reversible Immobilization of Asian Small-Clawed Otters with Medetomidine and Ketamine. Veterinary Record 128: 86-87
  • Nachtigall, P.E. (1969). Visual Size Discrimination in the East Asian Clawless Otter (Amblonyx cinereus) in Air and Under Water. Proceedings Of The Sixth Annual Conference On Biological Sonar And Diving Mammals pp 83-86
  • Nelson, G.H. (1983). Urinary Calculi in Two Otters (Amblonyx cinerea). Journal of Zoo and Wildlife Medicine 14: 72-73
  • Petrini,K.R., Lulich, J.P., Treschei, L. & Nachreiner, R.F. (1999). Evaluation of Urinary and Serum Metabolites in Asian Small-Clawed Otters (Aonyx cinerea) with Calcium Oxalate Urolithiasis. J Wildlife Med 30 (1): 54-63
  • Samuals, M.S. & Cook, R.A. (1991). Electrocardiography of the Asian Small-Clawed Otter (Aonyx cinerea). Zoo Biology 10 (3): 277-280
  • Warns-Petit, E.S. (2001). Liver Lobe Torsion in an Oriental Small-Clawed Otter (Aonyx cinerea). Veterinary Record 148 (7): 212-213
  • Weber, M.A. & Garner, M. ( 2002 ). Cyanide Toxicosis In Asian Small-Clawed Otters (Amblonyx cinereus) Secondary To Ingestion Of Loquat (Eriobotrya japonica) Journal of Zoo and Wildlife Medicine 33 2 : 145 - 146

Captive Studies: Behaviour

  • Nair, S. & Agoramoorthy, G. (2001). Mating- and Birth-Related Behaviour in Captive Asian Small-Clawed Otters. International Zoo News 49 (1/14)
  • Pellis, S.M. (1984). Two Aspects of Play-Fighting in a Captive Group of Oriental Small-Clawed Otters Amblonyx cinerea. Zeitschrift für Tierpsychologie 65: 77-83
  • Prima, C.L. (1992). Weaning Behaviour in the Oriental Small-Clawed Otter Aonyx cinerea at the National Zoological Park, Washington, D.C.. International Zoo Year Book 31: 245-250


  • Koepfli KP, Wayne RK (2003). Type I STS markers are more informative than cytochrome B in phylogenetic reconstruction of the Mustelidae (Mammalia: Carnivora). Syst. Biol. 52 (5): 571–93. doi:10.1080/10635150390235368. PMID 14530127.
  • Koepfli, K.-P., R.K. Wayne 1998. Phylogenetic relationships of otters (Carnivora: Mustelidae) based on mitochondrial cytochrome b sequences. Journal of the Zoological Society of London 246, 401-416


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