The giant otter generally lives in family groups of three to ten individuals, composed of a monogamous, breeding pair and their offspring born during previous years (2) (6). These groups rest, play, travel, fish and sleep together. Members of the group use communal latrines where they rub their faeces and urine into the earth with their paws, in order to advertise the group's residency (2) (6).
Breeding can take place throughout the year, although most young are born during the dry season. Litter size varies from one to six cubs, following a 64 to 72 day gestation (7). The new cubs are cared for by both the adults and older siblings. At two to three weeks the cubs are put in the water by the female, and at three to four months the cubs begin hunting and travelling with the family. The young are weaned at six months, and are efficient hunters by the age of ten months, although they remain with the family group for at least another year; sexual maturity is attained at age 2.5 years, after which many young adults disperse (2) (5) (6).
The giant otter is diurnal. Although highly adapted to its amphibious lifestyle, and despite its clumsy appearance on land, giant otters may travel several hundreds of metres between areas of water (2) (6). The diet is composed almost exclusively of fish, but it is also known to eat caimans, anacondas, other snakes and even the occasional turtle (2) (6).