Amazon river dolphin widespread river dolphins. They are present in six countries in South America: Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, in an area covering about . The boundaries are set by waterfalls, such as the Xingu and Tapajós rivers in Brazil, as well as very shallow water. A series of rapids and waterfalls in the Madeira River have isolated one population, recognized as the subspecies "I. g. boliviensis", in the southern part of the Amazon basin in Bolivia. They are also distributed in the basin of the Orinoco River, except the Caroni River and the upper Caura River in Venezuela. The
Xingu River in the Xingu River Basin and it is estimated that the total is around 600 fish species, including many endemics. At least 193 fish species living in rapids are known from the lower Xingu, and at least 26 of these are endemic. From 2008 to 2018 alone, 24 new fish species have been described from the river. Many species are seriously threatened by the dam, which will significantly alter the flow in the Volta Grande rapids. In the Upper Xingu region was a highly self-organized pre-Columbian anthropogenic landscape, including deposits of fertile agricultural terra preta, black soil in Portuguese, with