Sotalia fluviatilis
Other names: 
  • Tucuxi
  • Sotalia
  • Gray dolphin
Maximum length: 
  • Male: 1.5m
  • Female: 1.5m
  • Calf: 0.7m
Maximum weight: 
  • Male: Unknown
  • Female: 53 kg
  • Calf: Unknown
  • Fish
Estimated population: 
IUCN Listing: 
CITES Appendix: 
CMS Appendix: 

The controversy surrounding the taxonomy of the Sotalia genus has finally been laid to rest. The two 'populations' have recently been formally recognised as separate species; S. fluviatalis, otherwise known as the tucuxi, is a freshwater species whilst S. guianensis is marine, and now known as the Guiana dolphin.  Further research is needed in order to establish the distribution limits of both Sotalia species in the mouth of the Amazon River and the Amazonian Estuary as well as in the Orinoco River. The tucuxi is known as the 'other dolphin' of the Amazon.


Individuals in the genus Sotalia are similar in overall appearance to the bottlenose dolphin although they are smaller, have a low triangular dorsal fin, broad flippers, and a narrow more pronounced beak. Colouration ranges from blue to grey with a lighter underside of white, grey, or pink. The tucuxi is generally smaller than the Guiana dolphin with individuals in the coastal populations up to 30% larger, although where their range overlaps it would be virtually impossible to distinguish between the two species.


Tucuxi are usually found in small groups of only a few individuals although they can also be seen in larger groups. They are extremely sociable and perform impressive acrobatics, including spyhopping, lobtailing, flipper slapping, and porpoising. They are, however, not known to bow-ride, are shy and difficult to approach. They make short dives, usually lasting 30 seconds to one minute. Tucuxi can often be found in mixed groups with boto, and as the only other cetacean species sharing the same habitat, they cannot be misidentified.


Tucuxi are known to be distributed throughout the Amazon basin and possibly also in the Orinoco River. Threats to this species include direct kills – because of perceived competition and traditional medicine use, although interestingly they are also protected in many parts of their range because of myth and legend - pollution, accidental bycatch and entanglement in fishing gear, human disturbance, habitat deterioration and fragmentation of populations by dam construction. Comprehensive population estimates are not available and the IUCN lists this species as Data Deficient (2008).

Distribution map: