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.
Discus fish are extremely social and are one of the few real schooling cichlids. They live in large groups in their native waters, and have a very advanced social behaviour. They need the social interaction to develop their character and behaviour to the fullest. It is therefore wise to keep in mind that you need topurchase a group of discus when starting with this fish, as they are among the higher priced species. A small group of 6-8 same sized specimens is ideal if your aquarium is large enough. Never add young, small size discus into an aquarium with significantly larger adults. The larger Discus will inevitably bully the younger fish, steal their food and leave them starving. Grow smaller discus in a separate tank and only add them to your larger discus when they are close to the same size
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).
Reproduction and sexual dimorphism:
There is no real sexual dimorphism for this fish. In breeding form varieties, solid red discus (red melon, red cover) females are generally redder than males. Another characteristic of Symphysodon species is their care for the offspring. As for most cichlids, brood care is highly developed with both the parents caring for the young. Additionally, adult discus produce a secretion through their skin, which the offspring live off during their first few days. This behavior has also been observed for Uaru species. However, when bred in captivity the offspring will tend to live off their parents secretion for up to 2 weeks
Symphysodon species inhabit the margins of floodplain lakes and rivers in the Amazon Basin of lowland Amazonia, 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 andTrombetas rivers. S. tarzoo occurs upstream of Manaus in the western Amazon.