Discus Fish
Symphysodon aequifasciatus
The undisputed King of the freshwater aquarium (20 cm). Perfect discoidal shape. Quiet, majestic and of extraordinary intelligence, but extremely vulnerable to pathogens, cold and nitrates. Suitable only for dedicated aquarists.
Water Temperature
28 - 31 °C
pH Value
5 - 7
Water type
Freshwater
Tank level
Middle
Adult size
20 cm
Minimum tank volume
>= 180 L
Minimum group
>= 1
GH
1 - 8 dGH
KH
1 - 4 dKH
TDS
25 - 160 ppm
Conductivity
39 - 250 uS/cm
Species description
Geographical Origin and Habitat: The treasure of the Amazon (Peru, Colombia, Brazil). They strictly avoid fast currents. Their stronghold consists of silent bays ('Igarapés'), Blackwater or Clearwater rivers, amidst dense tangles of semi-submerged branches in flooded rain forests.
Taxonomy and Morphology: Member of the Symphysodon genus. The aquatic icon par excellence: the body is literally a perfect disc, extremely laterally flattened (useful for slipping between vines and roots without being noticed). The forehead is steep, small and delicate lips suitable for grazing biofilm. Reaches 15-20 cm (6-8 inches) in diameter. Stationary and slow swimming.
Social Behavior: His Majesty. Discus have a mild, regal, and shy character. They live in rigid hierarchical groupings: they must imperatively live in schools of at least 5 or 6 specimens, under penalty of fatal stress or systematic bullying to the detriment of the weakest. They never persecute other fish in the tank, being placid giants. They can feed from the breeder's hands.
Coloration and Sexual Dimorphism: The pinnacle of hybridization. The original Wild possess warm ochre/brown shades covered by stupendous turquoise vermiculations or black bars (Heckel). Bred varieties range from solid blue (Cobalt Blue, Blue Diamond) to blinding fiery red (Marlboro Red, Pigeon Blood, Red Melon), to spotted patterns (Leopard). They possess conspicuous vertical black bands called 'stress bars' (absent in Pigeon strains) that they use to communicate the state of fear or dominance. Non-existent dimorphism outside of reproduction.
Care, breeding and tankmates
Aquarium Setup: Demands respect, calm, and volume. Minimum aquariums of 300 liters (75 Gal, better 100+ Gal) and above all TALL (minimum 50 cm / 20 inches of water column). The ideal setup is an essential biotope: very little light, very fine white sand bottom, and a gigantic barrier of hanging roots that covers three-quarters of the glass. They accept thick planted aquariums well, but this complicates the mandatory massive siphoning and hides food debris.
Diet and Feeding: Delicate but greedy omnivore. They forage by blowing water on the sand to flush out larvae. Frequent feeding in small doses. Offer excellent slow-sinking discus granules, top-choice frozen bloodworms and brine shrimp (enriched with preventive garlic and spirulina). Historically, beef heart paste is used, not recommended in community tanks and modern management because it irremediably pollutes the tank.
Water Quality: THE GREATEST OBSTACLE. Discus DO NOT TOLERATE the slightest pollution (Tolerated nitrates close to zero, max 15-20 ppm, absolute zero Ammonium). THEY REQUIRE almost sterile or osmotic water with low conductivity (GH 1-8). The pH must fall on the acidic side: 5.5 to 6.8. Finally, the TEMPERATURE: they live continuously between 28°C and 31°C (82-88°F). A stay at 25°C (77°F) debilitates them in days. Copious weekly (or daily for growing juveniles) water changes are the ritual of every 'Discus Keeper'.
Compatibility and Cohabitation: Roommates chosen with tweezers. Companions must: resist the 30°C (86°F) and never bother them while they eat slowly. Divine roommates: large schools of Cardinal or Rummy-nose Tetras, hatchetfish, Corydoras Sterbai (the only corys resistant to that heat), and rare tame Loricariids. Fast and voracious fish are forbidden, or plecostomus that might try to suck the mucus from their flat flank.
Aquarium Breeding: One of nature's most admirable parental cares. They lay on a cone, hatching occurs quickly. For the first three weeks, the cloud of microscopic fry LIVES EXCLUSIVELY BY EATING THE HYPER-PROTEIN MUCUS (discus milk) specially secreted by the dark epidermis of the two parents, alternating on the right and left flank.
Risks and Diseases: Disease-catching machines if kept poorly. Intestinal flagellates or Hexamita (noticed by white and filamentous feces, holes in the head), mycosis, stress from hierarchical bullying. A Discus that suddenly becomes very dark (black/gray), remains in a corner facing the wall, is seriously ill.
Geographic Origin and Distribution
The treasure of the Amazon (Peru, Colombia, Brazil). They strictly avoid fast currents. Their stronghold consists of silent bays ('Igarapés'), Blackwater or Clearwater rivers, amidst dense tangles of semi-submerged branches in flooded rain forests.
Origin
Selective breeding and cultivarsAmazon, Orinoco, and GuianasNorth America
Fish profile
- Temperament
- Semi-aggressive
- They have a calm, regal, and somewhat sensitive temperament. They are easily spooked by sudden movements, loud noises, or aggressive tank mates. When housed in a proper, peaceful environment, they are incredibly majestic and display a curious, interactive nature with their keepers.
- Diet
- Omnivore
- They are omnivorous with a strong preference for high-quality meaty foods like beef heart, bloodworms, and brine shrimp. In captivity, a balanced diet is achieved by combining specially formulated Discus pellets with frozen foods and vitamin supplements. Proper nutrition is critical for maintaining their brilliant coloration and robust immune system.
- Life expectancy
- 10-15 years
- Under proper care and in a well-maintained environment, Symphysodon aequifasciatus can live for 10 to 15 years in captivity. Achieving this longevity requires consistent water chemistry, pristine water quality, and a balanced diet. Neglecting water changes or allowing stressful tank dynamics can lead to diseases like Hole-in-the-Head or parasite infestations, which significantly reduce their life expectancy. Therefore, maintaining a strict care routine is essential for their long-term health.
- Adult size
- 20 cm
- The catalog's scalar value is 20 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 13.7 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Symphysodon aequifasciatus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- School
- They are best kept in a school of at least 5 to 6 individuals to establish a natural pecking order and reduce stress. Buying a group of juveniles and allowing them to pair off naturally is the most successful way to establish breeding pairs. Once a pair forms, they may become mildly aggressive towards others while defending their spawning site.
- Feeding frequency
- Twice daily
- Adults should be fed two to three times daily, while juveniles require even more frequent feedings, up to five times a day, for proper growth. Uneaten food must be removed promptly to prevent water quality degradation, which Discus are highly sensitive to. Consistent, high-quality feedings are key to avoiding stunted growth in younger specimens.
- Bioload
- Blue Discus produce a considerable bioload due to their large adult size and need for a rich, high-protein diet. Because they require pristine water conditions, this heavy waste production demands an exceptionally efficient filtration system. Frequent, often bi-weekly, large water changes are mandatory to keep nitrates exceptionally low and ensure their health.
- Flow
- Stagnant
- Originating from calm tributaries and flooded forests in the Amazon, they strongly prefer slow, gentle water movement. High flow rates will force them to expend too much energy, leading to exhaustion and disease. Filtration returns should be baffled or directed away from their primary swimming areas.
- Reproduction
- Oviparous
- Breeding is fascinating but challenging, requiring dedicated pairs and pristine, soft, acidic water. After the eggs hatch, the fry famously feed on a specialized nutritious mucus secreted from the skin of both parents. Raising the fry demands meticulous water quality management and careful introduction of supplemental foods like baby brine shrimp.
- Compatibility & tankmates
- They are peaceful, slow-moving cichlids that do best with other calm, warm-water companions. Excellent tank mates include Cardinal tetras, Corydoras, and gentle South American dwarf cichlids. Aggressive, fast-swimming, or fin-nipping fish must be avoided as they will easily stress the Discus and outcompete them at feeding time.
- Tank level
- Middle
- Discus are predominantly mid-level dwellers, cruising majestically through the open areas of the water column. They appreciate tall vertical structures, like large Amazon swords or submerged branches, which provide a sense of security. They will venture to the bottom to forage for sunken food but rarely linger at the surface.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.3 ± 0.44 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.625
- Bayesian Length-Weight
- a = 0.02692, b = 3.02
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
