The Natural Habitat of the Discus
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During the rainy season, in which over 80 inches of rain can fall, the rivers can rise to be 40 feet deeper! This is partly due to the fact that there is very little slope to the rivers. The slope, or drop in elevation, is only 1/2 cm (about 3/8 inch) per kilometer (about 1/2 mile). The Amazon is about 2000 miles long. Tidal effects of the Atlantic Ocean can be noticed about 400 miles inland due to the small slope of the river. There are more than 1000 tributaries (connecting rivers) to the Amazon. The waters of the Amazon have a high turbidity; that is, visibility is limited to between 4 and 20 inches.

The tributaries with the high turbidity originate in the Andes Mountains, whereas some other tributaries are clear and originate in central Brazil. One major river, called the "Rio Negro" (starts in Northwest South America, north of the Amazon) does not have many suspended solids, but is brown or black in color due to humus or decaying plants (black water river). Conductivity in this river is about 10 and pH is about 4.5. The Amazon has a conductivity of about 60 and a pH of about 6.4 to 6.9. Discus don't thrive in these rivers, but rather in ponds and peripheral rivers and lakes that are left from these rivers after flooding. Most minerals in the water come from erosion. Lake water and various river waters differ in their mineral and life components.

There is usually little plant life in the brooks and streams in the forest, as sunlight does not penetrate the forest canopy. Plants in the water are usually the result of erosion, as are fruits and seeds in the water. Discus are not usually found here.

The large rivers originating in the mountains have many minerals from erosion and are fast flowing and do not have discus. The clear water rivers from central Brazil also have little underwater plant life due to poor sunlight reaching the water due to the forest. However, floating grasses and partially submerged plants do grow here. This fluctuates depending on the season.

The flooded areas, including the lakes, have a mixture of nutrients and organic matter and a food chain develops. Insects are plentiful. Discus are usually found in the flooded areas from the white water rivers. White water rivers are a combining of the clear water rivers with the black water rivers. Discus are usually found in waters containing many downed trees and places where roots of trees are exposed in the water and the discus can hide amongst these.

"DiskusBrief" magazine, Vol 1, June 1994, Issue 2, "Natural Habitat of the Discus Fish" by Professor Dr. Ulrich Saint-Paul, Germany

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