Discover fishes of the genus Symphysodon

Fish of the genus Symphysodon are commonly called discus. They belong to the group of "cichlasomatines," which includes several other species of compressed-bodied cichlids that inhabit similar biotopes. Examples include the genera Heros, Uaru, Pterophyllum, or Mesonauta.

Discus share some character traits with species from the previously mentioned genera. Rare among fishes, they have the peculiarity of producing mucus to feed their juveniles. Worldwide, only these fishes and Uaru exude this "milk" from their skin.

The number of discus species is still a matter of disagreement among scientists. According to Schultz, two species are recognized: S. aequifasciatus, divided into 3 subspecies, and S. discus Heckel found in the Rio Negro.

In 2006, a DNA-based study showed that the genus has two species: S. aequifasciatus and a new species, S. tarzoo, which includes the "green" and "blue" discus populations previously incorporated into the species S. aequifasciatus. The former S. discus, present east of the Purus arch, belong, according to this model, to the species S. aequifasciatus.

Finally, a 2007 DNA-based study also showed that there are actually three species of discus: S. discus, S. aequifasciatus, and S. haraldi. According to the latter, S. aequifasciatus is the only species found exclusively west of the Purus arch. S. haraldi is widely present around the mouth of the Amazon at the rio Iça. S. discus is limited to the Rio Negro and some tributaries. Hybridizations are common between S. discus and S. haraldi.

On Fishipedia, we have maintained the FishBase classification for the time being, awaiting resolution by scientists of these discrepancies.

A dynamic international trade is organized around the export of wild discus from the Brazilian Amazon. Despite the strong historical interest in discus in the aquarium hobbyist community, studies on the natural habitat of these fishes have long been absent. Much of the literature comes from captive experiments.