IUCN Otter Specialist Group . . . leading global otter conservation Last Update: Friday March 27, 2015
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Aonyx cinereus (Illiger, 1815), the Asian Small-Clawed Otter




The smallest of the world's otters, about 0.9m long, weighing around 5kg. This otter lives 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 molluscs 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 Identification 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 distribution 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 population which was previously thought to be isolated, exists in the hill ranges of the Western Ghats, and more recently they have been reported from protected areas in the Eastern Ghats which might better explain their distribution in South India. Their range in the Western Ghats too has increased with sightings and evidence being reported from the northern Western Ghats, well extending their range beyond the hills of Coorg and Ashambu. 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, in the western forests and southern marshes of Thailand, and in the Western Ghats of India where it appears to be the most common species of otter.

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 Team)

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 plantations 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 in some places, the vast aquaculture industry regards otters as pests and persecutes them directly. On a more positive note, there is increased evidence of otters using modified landscapes such as coffee and tea plantations in India and though habitat destruction might be of concern, direct threats need to be better understood.  They have even been recorded from storm water drains in Jakarta, indicating their adaptability to modified habitats. These otters are known to be highly elusive in disturbed landscapes, and this could potentially contribute to the perception of a decline in population.

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 inter-population 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 Bull7: 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 Bull1: 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.

  • PerincheryA., Jathanna, D., Kumar, A. (2011).  Factors determining occupancy and habitat use by Asian small-clawed otters in the Western Ghats, India.Journal of Mammalogy, 92 (4): 796-802.

  • Prakash N, Mudappa D, Raman TRS, Kumar A (2012). Conservation of the Asian small-clawed otter (Aonyx cinereus) in human-modified landscapes, Western Ghats, India. Tropical Conservation Science 5: 67–78.

  • Mohapatra, P.M., Palei, H.S., & Hussain, S.A., (2014). Occurrence of Asian small-clawed otter Aonyx cinereus  in Eastern India. Current Science 107(3): 367-370.

  • Punjabi, G.A., Borker, S.A., Mhetar, F., Joshi, D., Kulkarni, R., Alave, S.K., & Rao, M.K. (2015). Recent records of Stripe-necked Mongoose Herpestes vitticollis and Asian Small-clawed otter Aonyx cinereus from the north Western Ghats, India. Small Carnivore Conservation 51:51-55.


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 japonicaJournal 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 cinereaZeitschrift 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:10.1080/10635150390235368PMID 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



TRAFFIC, 9th December 2009: Otters feel the heat in Southeast Asia


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