Common Name: Acará Discus
Scientific Name: Symphysodon discus
Family: American Cichlids
Habitat: Amazon Basin in Brazil, Peru and Colombia
pH: min: 4.2 max: 6.2 (in aquarium: 6.5 – 7.5)
Temperature: min:22 max:28
Maximum Size: 20 cm (with good food and good water)
Sociability: Peaceful in shoals, but if you keep 2 or 3 the larger fish become aggressive.
Maintenance: Complex
Aquarium: Min: 50 liters per fish and High
Aquarium Zone: Surface and a half
Recommended Ration: MegaFood Tropical Basic accompanied by MegaFood Spirulina
Discus is the common name given to all freshwater fish species classified in the genus Symphysodon.
It belongs to the cichlid family and currently comprises two species and three subspecies. It is endemic to South America, where it can be found in rivers in the Amazon basin, in Brazil, Peru and Colombia.
Its main characteristics are its colors and the discoid shape of its body. It lives in schools and feeds on small crustaceans, larvae, insects and fruits in its natural habitat.
It reaches an average of 15 to 18 centimeters in length and inhabits small lakes and streams with calm, clear waters. The discus is one of the most popular freshwater fish in the world for its varied colors and its long dorsal and tail fin. It is an ornamental and extremely peaceful species, being suitable to be raised with fish with the same temperament; however, it is very demanding with regard to water quality, so it cannot always be kept in aquariums with many different species.
taxonomy
The discus belongs to the Heroini tribe, of the Cichlidae family, in the order Perciformes, which is still little studied. It was described by the Austrian zoologist Johann Jakob Heckel in 1840 as Symphysodon. The exact phylogenetic position of this genus among the others belonging to the Heroini tribe is unknown. The type species of this genus is Symphysodon discus.
The specific name Discus refers to its discoid form, while its generic name, Symphysodon, is a Greek word. Symphys means growing in groups and odon means teeth, referring to their reduced dentition relative to other cichlids.
The genus includes only two species: Symphysodon discus (Disco-Heckel) and Symphysodon aequifasciatus (Disco-blue-brown), but recent studies carried out with their DNA have shown the possible existence of a third species, named by scientists as Symphysodon tarzoo; however the analyzes were not conclusive. The acceptance of this species is still being studied by researchers.
Subspecies
Three subspecies are currently recognized, based on genetic analysis. All were described by the American ichthyologist Leonard Peter Schultz in 1960, after the description of Pelegrin Franganillo-Balboa of the species Symphysodon aequifasciatus in 1904:
Symphysodon aequifasciatus axelrodi – Brown discus mite: It has a yellowish-brown body and a head with bluish streaks.
Symphysodon aequifasciatus haraldi – Blue discus mite: It has a light brown body, with strong blue streaks on the head, back and fins.
Symphysodon aequifasciatus aequifasciatus – Green Discus Acara: It has a blue-green body, with striking blue streaks on the head, back and fins.
Geographical distribution and habitat
The discus is native to the Amazon, but it can only be found in some countries in South America. The Heckel disc is found in the eastern part of the Amazon, mainly in the Nhamundá, Branco, Negro, Purus, Abacaxis and rivers Trumpets. The green disk has a restricted distribution to the western part of the Amazon, in the Japurá, Içá and Nanay rivers. The brown-disk and blue-disk subspecies are generally found in the Solimões, Amazon, Urubu, Juruá, Tefé, Coari, Uatumã, Trombetas, Tapajós, Jari and Tocantins rivers. The blue-brown disk can be found in the beds of Amazon rivers and in some hydrographic basins in Colombia and Peru, with a wider distribution of the genus.
They inhabit rivers with calm, shallow and clear waters, with abundant aquatic vegetation, submerged trunks and roots, being slightly warm, with acidic characteristics and low hardness. They live mainly in floodplain lakes and marginal lakes.
behavior and reproduction
The discus has a territorial behavior and does not carry out reproductive migrations. During the rainy season, they live alone or in small groups in deep water, but during the dry season they form large schools near fallen trees along the banks of the lakes.
It reaches sexual maturity at twelve months of age and spawns more than once a year, with about 1,500 eggs per spawn. At the time of reproduction, they form couples through sexual courtship, characteristic of cichlids. They usually lay eggs on large leaves or stones. During spawning, the female lays a small amount of eggs that will soon be fertilized by the male. pair maintains constant agitation of the water around them, fanning them with their fins, to ensure the necessary oxygenation. Then the parents are committed to cleaning them and keeping them safe until the larvae hatch.
Depending on the water temperature, the eggs hatch after two or five days and remain with the yolk sac for another three or four days, until they can swim freely. After hatching, the larvae are fed mucus released by their parents for two weeks. After this period, they can be fed with brine shrimp, but they will need their parents’ secretion for another thirty days. With approximately fifty days, they can be separated from adults.
Characteristics
The discus is generally referred to as The King of Aquarius. It is considered a small fish, reaching 15 centimeters in length. It has a laterally flattened body with a relatively long dorsal and caudal fin, which contribute to the discoid shape of its body. It has only one nasal orifice on each side of the nostril, a prostatic mouth and thick lips. Males are larger, more colorful and with the first dorsal fin rays thicker and longer. They do not have evident sexual dimorphism.
Their colors vary depending on the species and may have red, blue, green, brown, white and yellow tones, and currently there are about 600 variations. They have several rows of scales at the base of the dorsal and caudal fins, generally blue streaks throughout the body and eight to nine dark transversal bands over the body.
Threats / Diseases
Like many other fish, the discus is susceptible to infections such as parasites, mycoses, bacteriosis, viruses and even ectoparasites.
However, under natural conditions the infectious agents that infest them are not numerous enough to affect the health of the host, because the nutritional and physiological state of the fish is properly adjusted to the environment. Specifically for the discus, the following parasites are found : protozoa (Piscinoodinium pillulare, Ichthyophthirius multifillis, Costia necatrix, Trichodina), monogenetic metazoans (Dactylogyrus vastator and Gyrodactylus elegans), mycoses and bacterioses.
In captivity, four diseases attack the species more frequently, as well as other species:
Gastroenteritis: by Aeromonas hydrophila a gram-negative bacterium.
Hexamitosis: caused by protozoa such as Hexamita meleagridis and Hexamita symphysodonis.
Capillariasis: caused by the nematodes Capillaria pterophylli. It usually affects species belonging to the cichlid family.
Ichthyouris Infestation: Caused by parasites. Affects fish intestines.
Extinction risk
Despite not being on the IUCN Red List, the number of discus in the wild has declined on a large scale since the 1990s. for breeding in aquariums. Other factors of anthropogenic influence that contribute to the disappearance of the species is gold mining, which releases mercury into the water, deforestation and forest fires, as they increase the temperature of the region and prevent the formation of clouds, extending the dry period.
captive breeding
Discus discus bred in an aquarium.
The first discus bred in captivity date back to 1933. They were captured in the wild and died shortly after being introduced to the aquarium. It was from 1935 onwards that the first reports of specimens that reproduced in captivity and reached adulthood appeared. During this period, they were exported in small quantities to Europe and the United States. Larger exports took place after the end of World War II, when motorsports developed. However, it was only in the 1980s that a systematic activity of discus exploration began.
It is one of the most popular species in the world used for fishkeeping, as well as one of the most explored. However, they are very demanding about the conditions in which they live, and it is not advisable to maintain them by aquarists who have not yet mastered the control of the water parameters of their aquariums. They should be kept in large aquariums with a minimum of 20 liters for each specimen, in order to avoid territorial disputes. They are very sensitive in relation to water quality and prefer acidic pH water, around 4.2 and 6.2 and with a temperature around of 26 and 30°C.
As they are found in rivers with abundant aquatic vegetation and poor lighting, aquariums should have plants, decorated with logs and stones, and placed in low light places, to resemble their natural habitat. However, not all plants adapt to water temperature and low lighting, with some of the most suitable being the Pygmy Chain Swords (Echinodorus tenellus) and the Java Fern (Microsorium pteropus).
They should not be bred with aggressive species or species that eat quickly, as they can be attacked or end up not eating. They should be kept with fish with a temperament equal to yours and that are adapted to the same quality of water. The most suitable species are neons (Paracheirodon innesi), some species of tetras (Characidae), such as the cardinal tetra (Paracheirodon axelrodi), catfish (Siluriformes) and some cichlids (Cichlidae). They accept live and frozen foods well, as well as industrialized flake feed.