Family: Cichlidae, Subfamily Cichlasomatinae
Common Name: Discus
Origin and Habitat: Mainstream Rio Solimoes/Amazonas (Brazil), Rio Putumayo-Ica (Peru, Brazil, prob Colombia). Inhabits very quiet streams thick with aquatic plants and flooded forest.
Compatibility/Temperament: Should always be kept in a group of 5 or more except for breeding. Very peaceful, but will become territorial during all stages of spawning. A very sedate fish, that should never be maintained with active, boisterous or aggressive fish. Suitable companions are small catfish, characins (hatchetfish, larger pencilfish and splash tetras, medium tetra), rasbora (Trigonostigma sp), dwarf cichlids. Although they occur sympatrically in their habitat, discus should not be kept with angelfish primarily because of the more aggressive feeding habits of the angelfish that may prove detrimental to the health of the discus [source: Jack Wattley]. Do see that fishes selected for tankmates share similar water conditions with respect to warmer waters that these fish prefer.
In nature, feeds on insects, worms, crustaceans and plant matter. In the aquarium: prepared foods other than flake, especially one of the specific discus preparations; frozen daphnia, artemia (brine shrimp), bloodworms, beef heart, squid; live blackworms, mosquito larvae, daphnia and artemia. Make sure to feed beef heart and worms sparingly to minimize chances of the discus getting intestinal parasites. As varied a diet as possible will ensure better health.
Ask the dealer what foods the fish are eating and ask if they will feed the fish in your presence. try and purchase some foods that the fish are eating as well as providing a varying diet.
Attains 6 inches (15 cm).
Minimum Tank Suggestion
48 inches in length, 75 gallons.
Water parameters for Discus
Soft (< 2 dGH), acidic (pH 4.2-6.2) water, temperature 26-30C/79-86F. Hardness and pH ranges are for wild-caught fish; tank-raised fish bred locally will likely be adapted to locat water parameters. The majority of these fish will do poorly in temps much below 80 degrees F. When kept in cooler temps,, growth is slower,digestive process is slowed and possible bloating /constipation can occur. Is also possible that immune system could be compromised thus making fish more suceptible to disease.
The subject species is one of two very closely related [see discussion below]; the other, S. discus has a separate profile.
The two nominal species currently recognized can be distinguished by colour pattern. Symphysodon discus has a distinct pattern of dark undulating lines covering the sides and a dark vertical bar across the middle of the side much more intense than the other vertical bars. Symphysodon aequifasciatus has all vertical bars similar in width and intensity; horizontal stripes do not show in preserved specimens except occasionally on the nape and on the anal fin base [Kullander]. Kullander has noted that life colours vary considerably in this species but how this correlates to geographical distribution, environmental conditions, sex and age of the fish remains to be investigated. Symphysodon aequifasciata is smaller at maturity than S. discus.
Most of the commercially available discus in the hobby are not true wild species. Heiko Bleher has noted that most of the so-called hybrids in the hobby are derived from the species he names S. haraldi (the blue/brown discus); Ready, Ferreira & Kullander (2006) consider this species to be S. aequifasciatus. The term "so-called hybrids" is used because strictly speaking biologically, a hybrid is the result of the breeding of two fish from different taxa. However, in common parlance, fish resulting from the crossing of two fish from different populations, breeds or cultivars within the same species are also referred to as "hybrids." Most (but not all) of the commercially available discus are within the latter group.
The first three of the photos below are of wild S. aequifasciatus, (upper to lower) the blue, brown and green forms. The fourth photo is a "hybrid" fish owned by Aunt kymmie (forum member).
Gender can be ascertained externally only during spawning; the papillae of the male is pointed, and that of the female rounded and blunt. There are some new ways of sexing this fish with geometrical lines, yet it is a new theory and hasn't been proven widely throughout the community. Like many other cichlids, discus form socially monogamous pairs and undertake bi-parental care of their broods (Matthaeus, 1992). Symphysodon and Uaru are unique among fishes in producing nourishing mucus that the newly hatched fry graze on. This mucus, known as 'discus milk', is exuded from the hypertrophied skin of both parents and is apparently essential for larval growth (Hildemann, 1959) [from Crampton, 2008].
This species was described in 1904 by J. Pellegrin who named it Symphysodon discus aequifasciata, which means this would be a subspecies of S. discus. The fish was subsequently raised to distinct species status.
The number of discus species has been a subject of disagreement for some time. Schultz (1960) published the first revision of the genus, and recognized two species on the basis of pigmentation: S. aequifasciatus and S. discus. He also divided S. aequifasciatus into three subspecies based on pigmentation: S. aequifasciatus aequifasciatus ('green' discus), S. a. haraldi ('blue' discus) and S. a. axelrodi ('brown' discus). Kullander (1996) determined the subspecies were invalid. Bleher et al. (2007) considers Symphysodon haraldi as a distinct species [see following].
Ready et al. (2006) proposed that the genus contains two distinct lineages corresponding to the species S. aequifasciatus [the eastern range fish] and a new species S. tarzoo [the western range fish]; the latter corresponds to the subspecies "described" by Lyons in 1959 as S. discus tarzoo. Ready et al. note that they found no significant genetic differences between the two existing eastern species S. discus and S. aequifasciatus, which suggests the species are either very closely related or they may be a single variable species. Without further examination of specimens, they are not proposing to synonymize S. aequifasciatus with S. discus, i.e., the two distinct species remain for the present. The result is there are three recognized species, S. discus (the Heckel Discus), S. aequifasciatus (the Blue Discus) and the new S. tarzoo (the Green Discus).
Bleher et al. (2008) also recognizes three species, though differing in the names: S. discus (the Heckel Discus), S. aequifasciatus (the Green Discus) and S. haraldi (the Blue Discus). In both Ready and Bleher the "brown" or "common" discus is the same as the Blue Discus. And both studies used mitochondrial DNA sequence data.
Etymology: Symphysodon, from the Greek symphysis [=grown together] and odous/odon [=tooth], referring to the few teeth situated where the two jaw halves meet. The species epithet aequifasciatus comes from the Latin aequus [=same or equal] and fasciatus [=band, girdle], referring to the equally wide dark stripes across the flanks, which differs from S. discus. The epithet tarzoo is a contraction of the name Tarpon Zoo, the ornamental fish exporting firm in Leticia, Colombia.
Bleher, H., K.N. Stolting, W. Salzburger and A. Meyer (2007), "Revision of the genus Symphysodon Heckel, 1840 (Teleostei: Perciformes: Cichlidae) based on molecular and morphological characters," Aqua--International Journal of Ichthyology, Vol. 12, No. 4, pp. 133-174.
Crampton, William G.R. (2008), "Ecology and life history of an Amazon floodplain cichlid: the discus fish Symphysodon (Perciformes: Cichlidae)," Neotropical Ichthyology, Vol. 6, No. 4.
Kullander, S.O. (1996), "Eine weitere Ubersicht der Diskusfische, Gattung Symphysodon Heckel," DATZ Sonderheft Diskus: pp. 10-16.
Ready, J. S., E.J.G. Ferreira and S.O. Kullander (2006), "Discus fishes: mitochondrial evidence for a phylogeographic barrier in the Amazonian genus Symphysodon (Teleostei: Cichlidae)," Journal of Fish Biology (2006) 69 (Supplement B), pp. 200-211.
A Guide to Choosing Discus:
1. Size of their eyes
The size of the eyes should be small in proportion to their body. If they seem bigger, then there is a sign that the discus are already stunted. Stunted fish tend to have enlarged eyes and this could indicate improper care,runts, or cullled fish.
They shouldn't look like the shape of a football which again signals a sign of stunted growth. Consider also their finnage, are the fins round-looking? Round appearance of the fins indicate the fish are healthy and don't have deformed fin formation.
Look for fish that are wide across the forehead and this thickness should continue to near the tail. Look to see that the eyes are not chipped,fins are all uniform in length and held erect. Clamped fins,chipped eyes, or fishes that appear very dark should be avoided. Look to see that both gills are functioning, and that flesh inside the gills is red as opposed to pink or white.
Look to see that no pitting of skin is present around the head area which may be indication of sick fish. Look to see if possible,, that poop is solid as opposed to stringy which could be indication of internal parasites.
Fish should be active and come to the front of the glass at feeding time , avoid fishes that sulk in the corners of the tank and or refuse to eat.
Ask the dealer what foods are offered and ask him/her if they would feed the fidhes in your presence. again ,avoid fish that do not rise to accept food or that remain sulking near the back of tank.
When the discus are young(below 4 inches), their colors aren't fully developed. However if you see discus with bright colors at a size of below 4 inches, then the discus may have been injected with hormones. The use of hormones to improve coloration is rather impractical.
Does the discus look healthy? Discus with very dark coloration(depending on the strain) are probably sick or severely stressed. Check their anus. Are there white stringy poo? They are a sign of the presence of intestinal parasites.
When buying discus, it is recommended to buy the biggest you can afford. Anything smaller than 4 inches can be difficult to keep alive as their immune systems are not fully developed making them rather vulnerable to diseases. Young discus should receive three to four small feedings per day taking care to remove what isn't eaten within 30 minutes.
If at all possible, always buy fish raised by a local breeder. These fish will be adapted to your water parameters. And local breeders will likely be far more helpful with advice.
A lot of pet stores sell "pairs" of discus. This is not a wise practice as discus tend to be choosy of their partner in nature. It is better to have a group of 5 or more and let the fish select their mates.
The following members have contributed to this profile: Byron, 1077, fjsedajr
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