Asian small-clawed otter

The Asian small-clawed otter (Aonyx cinereus), also called oriental small-clawed otter and small-clawed otter, is an otter species native to South and Southeast Asia. It has short claws that do not extend beyond the pads of its webbed digits. With a total body length of 730 to 960 mm (28.6 to 37.6 in), and a maximum weight of 3.5 kg (7.7 lb), it is the smallest otter species.

The Asian small-clawed otter lives in riverine habitats, freshwater wetlands and mangrove swamps. It feeds on molluscs, crabs and other small aquatic animals. It lives in pairs, but also has been observed in family groups with up to 12 individuals.

It is listed as Vulnerable on the IUCN Red List, and is threatened by habitat loss, pollution, and in some areas also by hunting.

Taxonomy

The Asian small-clawed otter was first described by Johann Karl Wilhelm Illiger in 1815. Over the years, scientists have given it several different names. In 1832, Constantine Samuel Rafinesque named a uniform-colored otter from Assam. Thomas Horsfield described two small-clawed otters from Java in 1824. In 1940, Reginald Innes Pocock named a dark brown otter from Virajpet in South India.

Phylogeny

Studies show that the Asian small-clawed otter is closely related to the Lutrogale genus. It shares a common ancestor with the African clawless otter and the smooth-coated otter. In Singapore, some Asian small-clawed otter females have mixed with smooth-coated otter males, creating hybrid otters that still carry genes from their small-clawed ancestors.

Characteristics

The Asian small-clawed otter has deep brown fur with some lighter coloring on its back and belly. Its face has special long hairs near the nose and small, oval-shaped ears. The otter's paws are narrow and have short, webbed digits, with very short claws that sometimes are not present at all.

This otter is the smallest otter species in Asia. Its body measures between 470 to 610 mm (18.4 to 24 in) long, not counting the tail, which adds another 260 to 350 mm (10.2 to 13.6 in). Adults in captivity usually weigh between 2.7 to 3.5 kg (6.0 to 7.7 lb).

Distribution and habitat

The Asian small-clawed otter lives in parts of India to Southeast Asia, including islands like Sumatra, Java, Borneo, and Palawan. It enjoys freshwater wetlands such as swamps, winding rivers, rice fields, and areas near the coast like estuaries, lagoons, and tidal pools. You can find it in places like West Bengal, Assam, and Arunachal Pradesh.

In some areas like Karnataka, the Nilgiri, and Palni hills in Tamil Nadu, it lives in shallow mountain creeks up to 2,000 meters. In West Java, it likes slow-moving irrigation channels and rice fields with plenty of plants for hiding. It also lives in mangrove forests. In February 2025, people spotted it in Dadeldhura District in far-western Nepal.

In the 1980s, a few of these otters escaped from captivity in England and started living in the wild there. This probably happened because the native Eurasian otter came back.

Behaviour and ecology

The Asian small-clawed otter is mostly active after dark and lives in groups of up to 15 individuals. These otters communicate using many different calls, yelps, and whimpers. When disturbed, they make loud noises to get help from others.

When swimming, they use their front limbs to row and their back limbs to paddle. Under water, they move by wiggling their bodies and tails. In places where they feel safe, they rest on grassy or sandy banks, enjoy the sun, and clean themselves.

Diet

The Asian small-clawed otter mainly eats crabs, mudskippers, and certain fish. Their diet changes with the seasons. They also eat snakes, frogs, insects, rats, and different kinds of fish found in rice fields. In some places, they have been seen leaving shellfish in the sun to make them open before eating them.

Reproduction

Studies of these otters in captivity show that they usually mate for life. Females have a cycle of about 28 to 30 days before they can mate, which lasts between one and 13 days. Mating usually happens in the water. After mating, it takes about 62 to 86 days before the babies are born. About two weeks before birth, both parents build a nest using grass, hay, or straw.

Litters can have between one and seven pups. When born, the pups cannot see and weigh between 45.6 and 62.5 g. Their eyes open after about five weeks. The pups start exploring outside the nest at ten weeks and begin to paddle in shallow water with their mother’s help at around three months. They become fully independent at four to five months.

Threats

The Asian small-clawed otter faces dangers because some people hunt them for their fur. Their homes, like special forests and water areas, are also being lost to make space for farms and buildings. In places like India, cutting down trees and pollution in rivers add to these problems.

These otters are also often taken illegally to be sold as pets. Many were offered for sale online in several countries, and some were caught trying to be smuggled across borders.

Conservation

The Asian small-clawed otter is very protected. It was listed on a special list called CITES Appendix II, and now since August 2019, it is on CITES Appendix I, which gives it even stronger protection against being sold or traded internationally.

In captivity

In 1983, a group of zoos and aquariums started a plan to help study and breed these otters in zoos. In Europe, Zoo Basel keeps Asian small-clawed otters together with Indian rhinoceros, and in Tallinn Zoo, they share their space with a binturong. Some otters can develop a bone problem called osteoporosis, which affects their bones.