Like cichlids from the genus Pterophyllum (angelfish), all Symphysodon species have a laterally compressed body shape. In contrast to Pterophyllum, however, extended finnage is absent giving Symphysodon a more rounded shape. It is this body shape from which their common name, "discus", is derived. The sides of the fish are frequently patterned in shades of green, red, brown, and blue. Some of the more brightly marked variants are the result of selective breeding by aquarists and do not exist in the wild.Discus typically reach up to 12.3–15.2 cm (4.8–6.0 in) in length,but captives have been claimed to reach 23 cm (9 in). Adults generally weigh 150–250 g (5.3–8.8 oz). No clear sexual dimorphism is seen for this fish, but males may reach a larger size than females.In breeding form varieties, solid red discus (red melon, red cover) females are generally redder than males.