Cichlids · Advanced care
Discus
Symphysodon spp.
Discus is rated advanced here because of its adult size, water range and social needs. Plan the aquarium around adult size, territory and sight breaks rather than shop size. Large, social and warm-water; demands excellent maintenance and stability.

Is Discus a good aquarium fish?
Discus reaches about 18 cm as an adult, so plan around the adult fish rather than the juvenile size seen in shops. The suggested minimum of 75 US gallons assumes suitable filtration, open swimming space and routine maintenance.
Generally peaceful in a suitable community. Keep the recommended group of at least 5 fish and avoid mixing it with tank mates that need a very different temperature, water chemistry or swimming level.
Water and aquarium setup
A stable temperature of 27–30°C and pH of 5.5–7.0 are the working ranges in the planner. Stability and clean, oxygenated water matter more than chasing a single target number.
Break up sight lines with rock, wood or plants and reserve territory before adding fish. Breeding pairs can change a peaceful community quickly.
Diet
A varied omnivore or carnivore diet of quality pellets, frozen foods and occasional treats.
Compatibility notes
Large, social and warm-water; demands excellent maintenance and stability.
Use the Stocking & Bioload Planner to check a proposed community. Its estimated bioload value for one adult discus is 31.97 units; this is a planning heuristic, not a replacement for testing nitrate.
Common mistakes
- Planning around the shop size instead of the adult size.
- Adding a schooling fish in a group smaller than its social minimum.
- Ignoring the tank's length, floor area or lid because the gallon number looks adequate.
- Adding fish before the aquarium is cycled and ammonia and nitrite are consistently zero.
Care ranges are conservative summaries of commonly cited husbandry references. Individual fish, strains and local water can differ; monitor the aquarium and adjust the plan gradually.
Photo source: Bernard Spragg. NZ from Christchurch, New Zealand · Public domain. The local copy is resized for page performance.