Green Discus
Symphysodon tarzoo
The wild 'Green Discus'. Discoid cichlid (18 cm) famous for its delicate green base coloration and showy red spots. Extremely demanding regarding hygiene and temperature (30°C / 86°F).
Water Temperature
28 - 32 °C
pH Value
5 - 6.5
Water type
Freshwater
Tank level
Middle
Adult size
18 cm
Minimum tank volume
300 L
Minimum group
5 - 6
GH
0 - 5 dGH
KH
1 - 2 dKH
TDS
10 - 95 ppm
Conductivity
16 - 148 uS/cm
Species description
Geographical Origin and Habitat: Populates the western Amazon (basins of the Rio Japurá, Putumayo, Tefé). Strictly associated with flooded areas where fallen branches form intricate underwater 'galleries'. Navigates slowly among the shadows in weakly flowing waters, escaping predators.
Taxonomy and Morphology: Recognized by recent studies as a separate species from S. aequifasciatus. The shape is the iconic flat disk, almost perfectly circular, highly compressed. Small mouth to graze invertebrates. Can reach 15-18 cm (6-7 inches) in diameter. The undisputed King of the freshwater aquarium.
Social Behavior: Very peaceful and highly gregarious. Isolated Discus get sick from lethal stress. They imperatively require a school of at least 5-6 specimens. In the school, a rigid but quiet hierarchy is established, based on fake frontal charges. They are easily frightened by sudden movements or shadows.
Coloration and Sexual Dimorphism: Extraordinary. Yellow-olive or light brown body base tending to mint green. It is crossed by 9 dark vertical bands (more or less visible depending on mood). The unique feature of the Tarzoo are the dense blood-red spots concentrated in the anal, ventral and caudal area. Turquoise streaks decorate the snout. No visible dimorphism.
Care, breeding and tankmates
Aquarium Setup: Demands a monumental and tall aquarium (minimum 150 cm x 50-60 cm / 60 x 20-24 inches high, 400 liters / 100 Gal). Ideal biotope: bare fine sand bottom, majestic bogwood roots falling from above to shade (fallen branch style), and Echinodorus (Amazonian plants). Subdued lighting to reduce stress.
Diet and Feeding: Very delicate. Demanding benthic grazers. Often disdain granules if not slowly accustomed. They must eat mashes based on shrimp, mollusks, spirulina (avoid mammalian beef heart in the long run), and mountains of frozen bloodworms and brine shrimp. Multiple modest daily meals spur appetite.
Water Quality: THE CRITICAL PARAMETER. Ultra-sensitive fish to ammonia and nitrates. The water must be feverishly hot (constant 28°C - 32°C / 82-90°F) to avoid lethal intestinal blocks. Weakly acidic or strongly acidic pH (5.0 - 6.5) and very low hardness (GH < 5). Copious and close water changes (up to 30-50% weekly in case of growth).
Compatibility and Cohabitation: Perfect master of docile Amazonian community tanks (Discus Tank). Companions of choice: Cardinal Tetras (often act as reassuring 'dither fish'), large schools of warm Corydoras (e.g. C. sterbai), calm Geophagus and algae-eating Loricariids. NEVER insert nervous cichlids or fast fish that would steal food.
Aquarium Breeding: One of the most touching parental cares in nature. They spawn on a cone or smooth root. The newly hatched larvae, unable to swim freely, stick to the sides of the parents and feed by grazing for weeks on the hyper-protein epithelial mucus secreted by the father's and mother's skin. Extraordinary to observe.
Risks and Diseases: Prone to Tuberculosis and the infamous Hole in the Head disease (Hexamitiasis) caused by chemical stress and vitamin deficiency. Lethal gill parasites if temperatures drop or hygiene decays.
Geographic Origin and Distribution
Populates the western Amazon (basins of the Rio Japurá, Putumayo, Tefé). Strictly associated with flooded areas where fallen branches form intricate underwater 'galleries'. Navigates slowly among the shadows in weakly flowing waters, escaping predators.
Origin
Tropical oceans and reefsAmazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- Green Discus have a calm, regal, and somewhat timid temperament, especially when first introduced to a new tank. They require a serene environment and will display stunning colors and interactive behavior once settled and comfortable. They are highly sensitive to their environment and will quickly show signs of stress if conditions decline.
- Diet
- Omnivore
- In their natural habitat, they consume a variety of small aquatic invertebrates, insects, and plant matter. In captivity, they require a high-quality varied diet of specialized pellets, frozen bloodworms, and vitamin-enriched brine shrimp. Providing a diverse and nutritious diet is key to bringing out their stunning green and red spotting.
- Life expectancy
- 8-12 years
- Symphysodon tarzoo, commonly known as the Green Discus, typically lives between 8 and 12 years in captivity under optimal care conditions. Achieving this lifespan requires maintaining very stable, soft, and acidic water parameters along with a high-quality, varied diet. Poor aquarium maintenance, fluctuations in pH, or stress from unsuitable tankmates can significantly shorten their lifespan. Consistent care and a peaceful environment are critical for helping these beautiful cichlids thrive.
- Adult size
- 18 cm
- The catalog's scalar value is 18 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 16.3 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Symphysodon tarzoo (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 schooling fish that should be kept in groups of six or more to establish a healthy social dynamic. Keeping them in large groups disperses aggression and allows natural pairs to form without forced pairing. A dominant fish will usually establish itself, but severe bullying is rare in properly sized groups.
- Feeding frequency
- Twice daily
- Adult Green Discus should be fed two to three times daily, while growing juveniles need up to five feedings. Their diet must be rich, but care must be taken to promptly remove any uneaten food to protect water quality. Consistent feeding of high-quality foods prevents stunting and ensures a robust immune system.
- Bioload
- The Green Discus creates a significant bioload due to its large adult size and heavy feeding requirements. Maintaining impeccable water quality through massive biological filtration and religious water changes is absolutely critical. Failure to manage their waste output effectively will quickly lead to disease and poor coloration.
- Flow
- Stagnant
- Originating from the very slow-moving waters of the western Amazon, they demand gentle, minimal water movement. Strong currents cause extreme stress, forcing them to hide and expend vital energy unnecessarily. Spray bars or gentle sponge filters are ideal for maintaining water quality without creating turbulent flow.
- Reproduction
- Oviparous
- Breeding Symphysodon tarzoo is challenging, requiring extremely soft, acidic water and dedicated breeding pairs. Like all Discus, the parents secrete a specialized nutritious mucus from their skin to feed the newly hatched fry. Successful breeding requires pristine water conditions and meticulous care during the fry-raising stages.
- Compatibility & tankmates
- They are peaceful, elegant fish that must be housed with very calm, slow-moving tank mates. Good companions include small characins, dwarf cichlids, and peaceful bottom-dwelling catfish that thrive in warm water. Avoid any fast, aggressive, or fin-nipping species that would easily outcompete and stress them.
- Tank level
- Middle
- They are classic mid-water column dwellers that prefer navigating around tall, vertical structures like submerged roots and large plants. They feel most secure when they have vertical shelter to retreat to when feeling threatened. They will feed from the substrate but generally avoid spending time at the very surface.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.1 ± 0.4 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.625
- Bayesian Length-Weight
- a = 0.0257, b = 3.11
- 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.
