The water mongoose is a good swimmer, although it often simply wades in to shallow water to acquire its daily food ration of frogs, crabs, shellfish, rats, snakes, mice and insects; it also eats birds and birds' eggs.
The mongoose uses the long-clawed digits of its forelegs to gouge crabs out of their shelters in river banks. Water mongoose are solitary, although adult females may be accompanied by juveniles. They will head for water if pursued, and will remain still, totally submerged except for the nose, in a reed bed until the danger is past.
When the marsh dries up, the mongoose will switch to a terrestrial diet; they will also wander some distance from water in search of new feeding grounds. Two young are born per litter.