Rio Negro (Amazon)
It is the largest blackwater river in the world. It is called Negro (Spanish and Portuguese for "black") because its waters are colored by particles of humus, which make them look much like tea.
Rio Negro has a very high species richness. About 700 fish species have been documented in the river basin, and it is estimated that the total is 800–900 fish species, including almost 100 endemics and several undescribed species. Among these are many that are important in the aquarium trade, including the cardinal tetra.
- Villa, Marco Aurelio. 1964: Aspectos geográficos del Territorio Federal Amazonas . Corporación Venezolana de Fomento. Caracas. 191p.
- Zinck, Alfred. 1986. Venezuelan rivers. Cuadernos Lagoven Lagoven, S.A. Caracas. 64p. ISBN 980-259-084-3
- Hales J. and P. Petry 2013. Rio Negro. Freshwater ecoregions of the world. Retrieved 12 February 2013