Discus are large, disc-shaped cichlids from the slow, warm, soft blackwaters of the Amazon, and are among the most demanding aquarium fish.
Their calm appearance hides exacting requirements that frustrate beginners.
Reaching 15-20cm across and living over a decade, they need clean warm water, careful diet and the company of their own kind.
Discus reward dedicated keepers with strong colour but decline quickly under neglect, which places them firmly in advanced territory.
Housing
Discus need a tall, deep, fully matured tank of at least 250L for a group, kept very warm at 28-30C, soft and acidic (pH 6.0-7.0) with low nitrate.
They are intolerant of pollution and unstable parameters.
Use gentle filtration, subdued lighting, driftwood and tall plants to mimic flooded forest.
Frequent large water changes, often several times weekly, are needed to keep nitrate minimal.
Quarantine and stability are critical; even small swings in temperature or chemistry cause stress and disease.
Diet
Discus are protein-hungry omnivores fed a varied menu of frozen bloodworm, brine shrimp, specialised discus pellets and traditional beefheart-based mixes.
Young, growing fish need feeding several times daily, which adds to the water-change burden.
Varied, quality feeding supports colour and growth, but heavy protein loads the water, so feeding and water management go hand in hand.
Avoid overfeeding and remove uneaten food promptly.
Feed measured portions to keep the warm, sensitive water clean.
Health
Discus are delicate and stress-prone, vulnerable to discus plague, hexamita and hole-in-the-head, gill flukes and bacterial infections, almost always linked to water quality or imported-stock disease.
Darkening colour, clamped fins and stringy white faeces signal trouble.
Strict quarantine of new fish, clean warm water and a low-stress group setting prevent most problems.
Sudden hiding, refusal to eat and rapid breathing call for immediate investigation.
Sourcing captive-bred fish from reputable breeders substantially reduces disease risk.
Temperament
Discus are peaceful, shy and intensely social, and suffer if kept alone or in too small a group; six or more lets them form a stable hierarchy and feel secure.
Lone or paired discus often become withdrawn and stressed.
Keep them only with calm, warm-water tankmates such as cardinal tetras and corydoras that tolerate high temperatures, avoiding boisterous or nippy fish.
Their timid nature means they are easily outcompeted at feeding time, so choose companions with care.
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