The pink river dolphin is a freshwater dolphin who lives in the Amazon and Orinoco rivers in South America. They are also known as Boto, and their scientific name is Inia geoffrensis. Although usually, they are pink, sometimes they are also gray, white or a mix of these colors. The pink dolphin of Hong Kong (Sousa chinensis) is another species with pink color mixed with gray, but they are entirely different species that live in far away from each other.
One of the theories that explain the reason for its unusual coloration is related to its social behavior. Some think that fights between some specimens, especially males, leave visible scars on their skin that turn pink with the passage of time.
Other researchers suggest that it is a natural way to camouflage themselves against predators, as reddish coloration is very common in the waters of their aquatic environment.