Symphysodon aequifasciatus
Discus
Discus are often called the king of the freshwater aquarium for their colour and shape, but they need pristine, warm, soft water maintained with real discipline. They suit experienced fishkeepers who enjoy a demanding, rewarding project rather than a first tank.
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At a glance
- Scientific name
- Symphysodon aequifasciatus
- Family
- Cichlidae
- Origin
- Slow-moving blackwater tributaries of the Amazon basin
- Lifespan
- 10–15 years
- Adult size
- 15–20 cm
- Weight
- Not typically measured
- Temperament
- Peaceful but easily stressed by poor water quality or boisterous tank mates
- Activity level
- Moderate; unhurried swimming through mid-water
- Social needs
- High; a settled shoal of six or more shows the best colour and confidence
- Intelligence
- Recognises individual keepers and feeding routines
- Noise
- Silent
Housing and environment
- Housing
- Tall planted aquarium of at least 300 litres for a shoal, with soft, warm, very clean water
- Space requirement
- Vertical swimming height and open mid-water areas between driftwood
- Temperature
- 28–30°C, notably warmer than most community fish
- Humidity
- Not applicable, aquatic species
- Exercise
- Provided by tank volume and gentle water movement
- Grooming
- Not applicable
Life stages and changing needs
Expanded care guidance · Updated 7 October 2026 · Not professionally reviewed
Young animals and settling in
Young discus are more sensitive to poor water quality than many other tropical fish and should only be introduced to a fully cycled, mature aquarium with soft, warm, slightly acidic water already matched to their needs. Ask the seller exactly what water conditions the fish are currently kept in and replicate these closely rather than assuming any heated tropical setup will do. Discus are shoaling fish and should be kept in groups of at least five, since a single or very small group is prone to stress and bullying.
Adult care and reproductive changes
Adult discus can grow to around twenty centimetres across and are slow growers that may take a year or more to reach full size, so patience and stable conditions matter more than rapid growth. Pairs may form within a group and defend a chosen spawning site; this is normal but can create pressure on less dominant fish in an undersized tank. Only established, already bonded pairs tend to do well kept as just two fish; otherwise maintain the full shoal.
Later life and changing needs
Discus can live for many years in a well-matured, stable aquarium with consistently good water quality. An older fish should keep its characteristic rounded, laterally compressed shape, bright colour and steady swimming. Thinning body condition, clamped fins, loss of colour, laboured breathing or a fish that isolates itself from the group needs water testing and an aquatic-vet or experienced discus-keeper opinion rather than being assumed to be a normal sign of age.
Diet and feeding
High-protein discus pellets, frozen bloodworm and beef heart mix in moderation
Offer a varied diet suited to this omnivorous species, including good-quality prepared discus foods and appropriate frozen foods such as bloodworm, given in small amounts several times a day rather than one large feed. Avoid sudden dietary changes and introduce any new food gradually while watching that every fish in the shoal, not just the boldest individuals, is feeding well.
Feed only what is cleared within a couple of minutes to avoid fouling the famously sensitive water chemistry this species needs; leftover food breaks down quickly and can push ammonia and nitrite upward in a system with little tolerance for fluctuation. Watch subordinate or newly introduced fish specifically, since a dominant individual can otherwise monopolise food at mealtimes.
Daily care and ongoing checks
Every day
Test and record temperature, pH, ammonia, nitrite and nitrate regularly, since discus need consistently warm water around twenty-eight to thirty degrees Celsius, a slightly acidic pH, and soft to medium hardness, and tolerate sudden shifts in these parameters poorly. Daily partial water changes are commonly used by experienced keepers to maintain the stable, clean conditions this species needs, alongside efficient filtration.
Regular maintenance and prevention
Observe each fish daily for colour, fin condition, breathing rate and whether it is engaging normally with the shoal, since a discus that withdraws or loses colour is often an early sign of a water-quality or health problem. Quarantine new fish before introduction, since discus are vulnerable to intestinal parasites and other diseases that can spread quickly through a shoal.
Behaviour and compatibility
Shoaling, gentle pair formation, feeding fry with body mucus when breeding
- With children
- Suitable to observe only; the tank's demanding water chemistry is not a beginner project
- With other animals
- Compatible with other calm, warm-water soft-water species such as cardinal tetras
- Training difficulty
- Not applicable
Health
- Hole-in-the-head disease
- Bacterial and protozoal infections from poor water quality
- Stress-related colour loss
Aquatic vets are rare; a specialist fish health service or experienced discus breeder is the usual resource
Special care requirements
Demands very frequent large water changes and stable warm temperatures; water quality lapses show up quickly as illness
Stable warm, soft, acidic water and shoal welfare
Discus need a shoal of at least five individuals and are not a solitary-tank species outside an already bonded breeding pair; a single discus in a community tank is likely to become stressed and withdrawn. Match tank water closely to the conditions the fish were already kept in, since an abrupt change in temperature, pH or hardness is a common cause of stress-related illness in newly acquired discus.
This species needs consistently warm water, roughly twenty-eight to thirty degrees Celsius, and tolerates poor water quality far less than many community fish, so prioritise filtration capacity and a disciplined water-change routine before stocking. Watch feeding closely across the whole shoal, since a dominant fish can otherwise leave quieter individuals thin and stressed without this being obvious at a glance.
Before you take one on
Sources and further guidance
These welfare and veterinary resources inform general husbandry advice; they do not certify this profile or replace a species-experienced professional. Confirm exact environmental settings and feeding plans for your animal.
Can your home meet discus needs?
- Plan for a lifespan of 10–15 years, including holiday cover and, where one is available, a vet familiar with this species. Lifespan ranges are not guarantees.
- Arrange the social setting before arrival. Social guidance for this species: High; a settled shoal of six or more shows the best colour and confidence. Do not assume another animal of any species is a suitable companion.
- Habitat priority for this species: Vertical swimming height and open mid-water areas between driftwood. Make sure your setup can provide this consistently. Check temperature and water quality with a thermometer and test kits rather than guessing.
- Key care point: Demands very frequent large water changes and stable warm temperatures; water quality lapses show up quickly as illness. Discuss diet and any specialist needs with the supplier, rescue and a vet who treats this species, and check local legal requirements before acquiring an animal.
Educational reference, not an individual diagnosis or a verified professional review. Read our editorial policy.
Guidance libraries and further reading
These organisations publish relevant guidance. Their links are further reading, not evidence that they have reviewed this page.