(1) Whitewater rivers pick up large amounts of sediments from the Andes giving the water a muddy-brown color. Whitewater receives its name from the white foam of the rapids of the upper regions. Whitewater river rivers lack abundant plant life. Most aquarium species are found in quiet, backwater areas like oxbow lakes. The water properties of white water rivers are: a pH from 6.8-7.1 and a dH of 3-5. The best example of a white river river is the Amazon River.
(2) Clear or blue water rivers are tributaries which flow through ancient Brazilian and Guyana rock beds where little sediment is released into the rivers. The waters of these rivers is very clear and allows plant growth. Clear water rivers have a pH of 6.9-7.5, and a water hardness of 5-12 dH. The Rio Xingu and the Rio Tocantins are such rivers.
(3) Blackwater rivers are nutrient poor and tea or black in color from the tanic acid released from decaying vegetation. Blackwater is crystal clear and has been compared to distilled water due to its lack of dissolved minerals. Blackwater rivers are acidic (6.0 pH) and soft, with little measurable water hardness (0 dH). The Rio Negro is the most famous of the blackwater rivers.
South American Cichlids differ greatly from one another in body shape, coloration, and survival habits. Since they differ so greatly, no general description of South American Cichlids, as a whole, can be accurately included.