The Argentine swamp rat is a semiaquatic rodent of waterside and flood-prone habitats. It is nocturnal, with a dark back and grayish-white underside.
Its fur is fine, soft, and glossy, dark brown to black above and grayish white below. The ears are small and rounded, and the relatively short tail is dark and furred.
This semiaquatic rodent is associated with watercourses and flood-prone microhabitats and is nocturnal. The identification key also records it from wet grasslands.
An extinction-risk assessment has not been added yet.