The two types of tucuxi have similar social groupings with 1-30 individuals. Groups often swim in perfect synchrony. The rates of the clicks are 10-70 per second when animal is moving. The short pulses and high rates of repetition allow distinction of objects at distances less then 15 cm. Whistling has also been reported in the wild riverine tucuxi, and a higher frequency whistle has been reported when the animals are agitated in captivity.
Aggressive behavior occurs amongst males during breeding season.
Habitat S. fluviatilis can be found in fresh or salt water. Marine S. fluviatilis are found in shallow and protected estuarine waters, bays, and mouth of large rivers. Riverine S. f. fluviatilis are found in the main channels of tributaries as well as in large lakes, but they do not enter flooded forest and avoid rapids. The greatest danger to both subspecies is incidental capture in the fishing nets belonging to large commerical fisheries. Other concerns are water pollution and hydroelectric dams.