Tucuxis are found in the Amazon drainage as far inland as southern Peru, eastern Ecuador, and southeastern Colombia. They occur in the main tributaries of the Amazon/Solimões River basin and they cross international boundaries in areas such as Leticia, between Brazil and Colombia. The species does not occur in the Beni/Mamoré river basin in Bolivia nor in the upper Rio Negro. Its putative presence in the Orinoco is controversial because of a stretch of rapids and waterfalls that are suspected to block the species movements to this area (Flores and da Silva 2009). During the flood season, Tucuxis may move into smaller tributaries, but apparently they do not move into the inundated forest to feed (as botos, Inia geoffrensis, often do), staying mainly in the main river channels, tributaries and lakes (da Silva and Best 1996). Tucuxis are largely sympatric with the Boto in the Amazon and Orinoco systems but generally do not interact with that species.