Symphysodon discus, the red discus or Heckel discus, is a species of cichlid endemic to the Amazon Basin of Brazil, where found in the lower Rio Negro, upper Uatumã, Nhamundá, Trombetas and Abacaxis.

[2] This species is essentially restricted to blackwater habitats with a high temperature of 26–32 °C (79–90 °F) and low pH of 4.2–5.2.

[3] This species grows to a length of 20 centimetres (7.9 in) SL.

[4] This species can also be found in the aquarium trade.

[4] Small fry of this fish feed on the mucus secreted by their parents.