Discus fish (Symphysodon)

Classification:

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Cichlidae
Subfamily:	Cichlasomatinae
Tribe:	Heroini
Genus:	Symphysodon

Picture:

About:
Symphysodon, colloquially known as discus, is a genus of cichlids native to the Amazon river basin. Due to their distinctive shape and bright colors, discus are popular as freshwater aquarium fish, and their aquaculture in several countries in Asia is a major industry.^[1][2][3][4] They are sometimes referred to as pompadour fish.
Species:

There are currently three recognized species in this genus:^[7]

• Symphysodon aequifasciatus Pellegrin, 1904 (Blue discus)
• Symphysodon discus Heckel, 1840 (Red discus or Heckel discus)
• Symphysodon tarzoo E. Lyons, 1959

Taxonomy[edit]

• 

  Symphysodon discus
  Discus are fish from the genus Symphysodon, which currently includes the above species.^[8] However, another review of the genus published in August 2007 suggested that the genus held these three species: S. aequifasciatus (the green discus), S. haraldi(the blue/brown/common discus), and S. discus (the Heckel discus).^[9] Further arguments have been made that S. tarzoo was not described in accordance with ICZNrules and thus should be considered invalid and replaced with S. haraldi,^[10] currently considered a synonym of S. aequifasciatus by FishBase.
  

  Captive strain
  Other (sub)species have been proposed, but morphometric data (unlike in Pterophyllum, the freshwater angelfish) varies as much between individuals from one location as across the whole range of all discus fish species. S. tarzoo was described in 1959 and applies to the red-spotted western population. S. aequifasciatus and S. discus, meanwhile, seem to hybridise frequently in the wild or have diverged recently, as they lack mitochondrial DNA lineage sorting but differ in color pattern and have dissimilar chromosomal translocation patterns. S. discus occurs mainly in the Rio Negro. Whether S. haraldi is indeed distinct from S. aequifasciatus remains to be determined; if valid it is widespread but it might just be a color morph.

  Location and habitat[edit]

  

  A map of the range (orange shading) ofSymphysodon
  Symphysodon species inhabit the margins of floodplain lakes and rivers in the Amazon Basinof lowland Amazonia,^[11] where it is part of the highly diverse Neotropical fish fauna.
  The three species of Symphysodon have different geographic distributions. S. aequifasciatus occurs in the Rio Solimões, Rio Amazonas and the Río Putumayo-Içá in Brazil, Colombia and Peru. In contrast the distribution of S. discus appears to be limited to the lower reaches of the Abacaxis, Rio Negro and Trombetas rivers. S. tarzoo occurs upstream of Manaus in the western Amazon.^{[citation needed]}

  Appearance[edit]

  

  Red turquoise discus
  Like cichlids from the genus Pterophyllum, all Symphysodon species have a laterally compressed body shape. In contrast to Pterophyllum, however, extended finnage is absent giving Symphysodon a more rounded shape. It is this body shape from which their common name, "discus", is derived. The sides of the fish are frequently patterned in shades of green, red, brown, and blue. The height and length of the grown fish are both about 20–25 cm (8–10 in).^{[citation needed]}

  Reproduction and sexual dimorphism[edit]

  

  Discus with two of its young nearby
  There is no real sexual dimorphism for this fish. In breeding form varieties, solid red discus (red melon, red cover) females are generally more red then males. Another characteristic of Symphysodon species is their care for the larvae. As for most cichlids, brood care is highly developed with both the parents caring for the young. Additionally, adult discus produce asecretion through their skin, which the larvae live off during their first few days. This behaviour has also been observed forUaru species. However when bred in captivity the larvae will tend to live off their parents secretion for up to 2 weeks.^[12]
• Species:
• Symphysodon aequifasciatus(blue discus)
•                                                                         Symphysodon aequifasciatus, the blue discus, is a species of cichlid native to rivers of the eastern Amazon Basin where it prefers deep waters, hiding between roots and in crevices in rocks.
  This species grows to a length of 13.7 centimetres (5.4 in) SL.
  This species can also be found in the aquarium trade as well as being important as a food fish for the local population.
• 
• Symphysodon discus(red discus or Heckel discus)
•                                                                                          Symphysodon discus, the red discus or Heckel discus, is a species of cichlid native to the Amazon Basin, where found near the mouth of the Rio Negro, in the lower Abacaxis River and lower Trombetas River.
  This species grows to a length of 12.3 centimetres (4.8 in) SL.
  This species can also be found in the aquarium trade.^[1]
•   Symphysodon tarzoo
•                                         Symphysodon tarzoo is a species of cichlid native to rivers of the western Amazon Basin where it prefers deep waters, hiding between roots and in crevices in rocks. This species grows to a length of 13.24 centimetres (5.21 in) SL. Symphysodon tarzoo differs in colouration from other discus species from the red spots on the anal fin and the body. The species was first discovered by Earl Lyons in 1959, and was named in 2006.^[1]