Symphysodon tarzoo, the green discus, is a species of cichlid endemic to Brazil; specifically, to rivers of the western Amazon Basin upriver from the Purus arch, although it occasionally occurs downstream.

[2][3] An introduced population in the Nanay River is based on stock from the Tefé region.

[4] The green discus is found in blackwater habitats with a high temperature of 27–30 °C (81–86 °F) and low pH of 4.8–5.9.

[2][6] S. tarzoo has red spots on the anal fin and body, which separates it from other discus species.

[7] The scientific name was coined by Earl Lyons in 1959, and the species was revalidated by pattern, morphology and mtDNA in 2006.