8. Symphysodon Discus
Unlike other aquarium fishes symphysodon discus fishes shows intelligent behaviors, that is displaying of different moods. This behavior of discus fishes makes them as a common aquarium fish. It is native to the Amazon basin of South America, found in blue, brown, green, reddish and golden colors. They are very social, always travel in groups. Sea turtles and large fishes are the main predators of discus fish.
Symphysodon, colloquially known as discus, is a genus of cichlids native to the Amazon river basin in South America. 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. They are sometimes referred to as pompadour fish.
Discus are fish from the genus Symphysodon, which currently includes the species S. aequifasciatus, S. discus and S. tarzoo, based on a taxonomic review published in 2006. A review published in 2007 largely came to the same result, but differed in nomenclature, as the species called S. tarzoo in the 2006 study was called S. aequifasciatus in the 2007 study, and S. aequifasciatus in 2006 was S. haraldi in 2007. Further arguments have been made that S. tarzoo was not described in accordance with ICZN rules and thus should be considered invalid and replaced with S. haraldi, currently considered a synonym of S. aequifasciatus by FishBase.
Other (sub)species have been proposed, but morphometric data 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.