Once found in 'large schools'
The species is found exclusively in freshwater habitat. In Nepal, it inhabits clear water and rapids. In Bangladesh and India, individuals live in rivers that flow slowly through the plains. The Ganges River dolphin favours deep pools, eddy counter-currents located downstream of the convergence of rivers and of sharp meanders, and upstream and downstream of mid-channel islands.
'Susu' shares its habitat with crocodiles, freshwater turtles and wetland birds, many of which are fish eaters and are potential competitors with dolphins.
In the 19th century, Ganges River dolphins were once found in 'large schools' close to urban centres along the river. Nowadays, groups are considerably smaller, and individuals may also be found alone. The average size of a number of groups surveyed recently in the Ganges River system was two individuals.
The young wean within their first year, and males reach sexually maturity at around 1.70 m (5.6 ft), when they are about 10 years of age. The oldest male animal on record was about 28 years old.
The gestation lasts from 9 to 11 months, and one calf is usually born, once every 2 to 3 years. There is no specific birth period, although females usually give birth from October to March, with a peak in December and January at the onset of the dry season.
The diet includes a variety of fish and invertebrates, namely prawns, clams, catfish, freshwater sharks, mahseers (except in India), gobies and carp. Ganges River dolphins normally chase surface dweller fishes and grovel mud dweller fishes in shallow water with the help of their long snout. They cannot chew and usually swallow their prey.