The marsh mongoose has dark brown fur and favours wetlands beside rivers and lakes.
Long, shaggy fur covers its neck, body and tail, while the fur on its hands and feet is short and sleek.
A two-year study in the Dzanga-Sangha forest of southwestern Central African Republic found it in swamp forest beside streams. In that study, it ate more aquatic prey than the other mongoose species compared.
An extinction-risk assessment has not been added yet.