* Brazil: The largest portion of their range is in Brazil, including the Amazon River and its tributaries.
* Peru: They are also found in the Peruvian Amazon, including the Ucayali and Marañón rivers.
* Colombia: They inhabit the Colombian Amazon, including the Caquetá and Putumayo rivers.
* Bolivia: They are found in the Bolivian Amazon, including the Beni and Mamoré rivers.
* Ecuador: They are found in the Ecuadorian Amazon, including the Napo River.
* Venezuela: A small population exists in the Venezuelan Amazon, near the border with Colombia.
* Guyana: A very small population exists in the Guyana portion of the Amazon.
While they are primarily found in the Amazon River basin, they are also found in some connected river systems, such as the Orinoco River in Venezuela.
It's important to note that their population is facing threats from habitat loss, pollution, and overfishing.