| Green discus | |
|---|---|
| |
| |
| Individuals from Nanay (above) and Japurá Rivers (below) | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cichliformes |
| Family: | Cichlidae |
| Genus: | Symphysodon |
| Species: | S. tarzoo
|
| Binomial name | |
| Symphysodon tarzoo Lyons, 1959
| |
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.[4] Although also known from whitewater, its preference for lentic habitats such as floodplains means that the water contain little suspended material (unlike main sections of whitewater rivers).[3][5]
This species grows to a length of 13.2 centimetres (5.2 in) SL.[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.[2][7] Later studies have confirmed its distinction, although some suggest the correct scientific name for the green discus is S. aequifasciatus (a name typically used for the blue/brown discus).[3][4] No natural (wild) hybrids are known between the green discus and its relatives.[2][4]
