It is native to the upper Orinoco and Negro Rivers in South America.

The Casiquiare river is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America.

Pseudolithoxus tigris is a species of armored catfish endemic to Venezuela where it is found in the upper Orinoco and Ventuari River basins.

The Casiquiare is a river distributary of the upper Orinoco, which flows southward into the Rio Negro, which in turn flows into the Amazon.

The genus has been reported from the upper Orinoco, the eastern, north-flowing Amazon tributaries, and the Tocantins River.

It is native to Venezuela and northern Brazil, particularly the upper Orinoco and Rio Ererê, a tributary of the Rio Negro.

The genus occurs in blackwater and whitewater habitats in the upper Orinoco and Rio Negro rivers of the Amazon basin.

Dekeyseria species are known from the Rio Negro, floodplain lakes of the Amazon, and upper Orinoco.

James Falmer and Roderick Thone, professional orchid hunters, with two Indian guides, had been following an obscure tributary of the upper Orinoco.

The Caura is a Blackwater river, like the Caroní, the Ventuari River and the upper Orinoco.