Which genus contains the freshwater aquarium fish commonly called discus?

Symphysodon is the genus containing the freshwater aquarium fish commonly called discus.

Discus are laterally compressed cichlids native to slow-moving waters of the Amazon Basin. Their rounded bodies and bright colour varieties have made them popular aquarium fish, while wild populations display patterns adapted to particular rivers and habitats.

The genus traditionally included several recognized species, including the red discus, blue or brown discus, and Heckel discus. Modern classifications and species boundaries have changed as researchers have combined morphological and genetic evidence.

Discus are sometimes confused with angelfish because both are South American cichlids with striking shapes and colours. Angelfish belong to Pterophyllum, however, whereas discus belong to Symphysodon. Discus are also notable for producing a nutritious mucus on their skin that their fry graze during early development.