The discus is multicolored with a compressed disc-shaped body. Depending on the fishing areas, the patterns include various shades of brown, blue, red, or green.
According to Schultz (1960), there are three subpopulations: - S. aequifasciatus aequifasciatus (green discus - mainly from the southern tributaries of the upper Amazon) - S. a. haraldi (blue discus - mainly from the northern tributaries of the upper Amazon) - S. a. axelrodi (brown discus - mainly from the lower Amazon)