The marsh mongoose's fur is dark reddish brown to black with white and fawn coloured guard hairs. The hair behind the neck and in front of the back is short, but longer on the hind legs and on the tail. Its muzzle is short with a fawn coloured mouth, short whiskers and a naked rhinarium. It has teeth. Its short ears are round. It has two nipples. Its feet have five flexible digits each with curved claws, but without any webbing. The soles of its feet are naked. Females measure in head-to-body length, and males, with a long tail. In weight, adults range from. Both sexes have anal glands in a pouch that produce a musky smelling secretion.
The marsh mongoose is. It is an excellent swimmer and can dive for up to 15 seconds, using its feet to paddle. On land, it usually trots slowly, but can also move fast. Radio-collared marsh mongooses in Kwa-Zulu Natal showed crepuscular activity, and were active from shortly after sunset until after midnight, but not during the day. A male marsh mongoose radio-collared in Dzanga-Sangha Special Reserve was most active in early mornings and late evenings. During the day it rested in burrows situated in dry areas above water and mud in dense cover of high grasses and climbing plants.
Feeding behaviour of eight captive marsh mongooses was studied in 1984. When the mongooses sighted prey in the water, they swam or walked towards it, used their digits to seek it out, but kept their heads above water. Once located, they grabbed it with the mouth and killed it outside the water. They killed rodents and frogs by biting them in the head, and occasionally also shook them. When finished eating, they wiped their mouths with the forefeet. They broke eggs by throwing them backwards between the legs. Scat of marsh mongooses collected around Lake St Lucia contained foremost remains of crustaceans, amphibians, insects and fish. Marsh mongooses were observed while carrying mudcrabs ashore. They removed the chelipeds and opened the sternum to feed on the body contents. They deposit scat at specific latrine sites located on low shrubs, on rocks or sand well away from the water edge. Scat of marsh mongoose collected in a rocky coastal habitat contained remains of sandhoppers, shore crab, pink-lipped topshell and Tropidophora snails. Research in southeastern Nigeria revealed that the marsh mongoose has an omnivorous diet. It feeds on rodents like giant pouched rats, Temminck's mouse, Tullberg's soft-furred mouse, grass frogs, crowned bullfrog , herald snake, mudskippers, insects such as spiders and Coleoptera, snails and slugs, Bivalvia, Decapoda as well as fruits, berries and seeds.
Reproduction
After a gestation of 69 to 80 days, females give birth to a litter of two to three young, which are fully furred. Their eyes open between the 9th and 14th day, pupils are bluish at first and change to brown at the age of three weeks. Their ear canal opens between the 17th and 28th day. Females start weaning their offspring earliest on the 30th day, and young are fully weaned by the age of two months.
Threats
In 2006, it was estimated that about 950 marsh mongooses are hunted yearly in the Cameroon part of the Cross-Sanaga-Bioko coastal forests.
