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. Scientists have used many names for it. In 1832, Constantine Samuel Rafinesque named an otter from Assam. Thomas Horsfield described two otters from Java in 1824. In 1940, Reginald Innes Pocock named an otter from Virajpet in South India.

Phylogeny

Studies show the Asian small-clawed otter is related to the Lutrogale genus. It shares ancestors with the African clawless otter and the smooth-coated otter. In Singapore, some females have mixed with smooth-coated otter males, creating hybrid otters.

Characteristics

The Asian small-clawed otter has deep brown fur with 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. You can find it on islands like Sumatra, Java, Borneo, and Palawan. It likes freshwater wetlands such as swamps, rivers, rice fields, and areas near the coast like estuaries, lagoons, and tidal pools. It lives 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. In West Java, it likes slow-moving irrigation channels and rice fields with plants for hiding. It also lives in mangrove forests. In February 2025, people saw 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. These otters talk to each other using many calls, yelps, and whimpers. When upset, 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 safe places, they rest on grassy or sandy banks, enjoy the sun, and clean themselves.

Diet

The Asian small-clawed otter mainly eats crabs, mudskippers, and some fish. Their food changes with the seasons. They also eat snakes, frogs, insects, rats, and different kinds of fish from rice fields. In some places, they leave 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 can mate after a cycle of about 28 to 30 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 being lost to make space for farms and buildings. In places like India, cutting down trees and pollution in rivers make things worse.

These otters are also sometimes taken illegally to be sold as pets. Some were offered for sale online, and others were caught trying to be smuggled across borders.

Conservation

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

In captivity

In 1983, zoos and aquariums started a plan to study and breed these otters in captivity. 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.