Discus cost $50 to $300 per fish and demand more than any common freshwater species in the hobby. They are also among the most striking — large round body, vivid color patterns, slow stately movement. People who keep them well usually have several years of experience first. People who try to keep them too early often spend $1,000 on dead fish in a season. This guide is for the people taking the step deliberately.
What makes discus demanding
Four factors compound:
- Water chemistry sensitivity — wild-type discus come from the Amazon’s blackwater tributaries. They evolved in soft, acidic, warm water.
- Stress sensitivity — discus shut down quickly under stress, going dark or losing color, and may stop eating for weeks.
- Group dynamics — pecking order matters. Singletons rarely thrive.
- Long-term commitment — adults live 10-15 years.
Tank requirements
Tank size
75 gallons is the minimum for a group of 5-6 discus. Some breeders argue 90+ gallons. The reasoning: discus are tall fish (8-9″ adult height) and need vertical swimming space, and water-quality stability is harder in smaller tanks.
Tank shape
Standard or tall is fine. Avoid long, shallow “breeder” tanks — discus prefer depth to length.
Temperature
82-86°F. Higher than most community fish tolerate. Plan tankmates accordingly. Heat reduces oxygen, so strong filtration and surface agitation matter more.
Water chemistry
This is where most discus failures begin.
For wild-caught discus
- pH 5.5-6.5
- GH 1-3, KH 0-2 (soft water)
- Some keepers use RO water with remineralization
For captive-bred discus
Most are now raised in harder, neutral water by breeders. Tap-water parameters work for many captive-bred lines, provided:
- pH stays stable (drift is worse than slightly-wrong-but-stable)
- Hardness is moderate (GH 4-12)
- Nitrate stays below 20 ppm
Always
- Ammonia and nitrite: 0
- Nitrate: under 20 ppm (more sensitive than most fish)
- Pristine water — discus react to organic pollution other fish ignore
Filtration and water changes
Heavy filtration is mandatory. A canister rated for double your tank size, or two filters running together. 30-50% water changes weekly minimum — many breeders do this daily for growth tanks. Use temperature-matched, dechlorinated water; sudden temperature drops kill discus.
Diet
Discus need higher protein than typical tropical fish.
- Quality dry food: Tetra Discus, Hikari Discus Bio-Gold, Saki-Hikari Discus, Cobalt Discus
- Frozen: bloodworms, mysis shrimp, brine shrimp — 2-3 times weekly
- Beef heart mixes: traditional discus food. Excellent for growth but pollutes water rapidly — feed sparingly, vacuum substrate after.
- Frequency: 2-4 times per day for young discus, 1-2 for adults
Group size and dynamics
Keep at least 6 discus together. Five works. Four is risky — the alpha bullies the bottom of the order. Pairs work but are unusual.
Watch for hierarchy stress: one fish hiding constantly, refusing food, color washed out. If it persists more than 2 weeks, that fish should be moved to another tank or rehomed.
Tankmates that work
- Cardinal tetras — tolerate the warm temperature, school beautifully alongside discus
- Rummynose tetras — temperature compatible, dense schooler
- Sterba’s corydoras — among the few cories that handle 82°F+
- Apistogramma — small dwarf cichlids that share water preferences
- L-number plecos — small plecos like L46 (zebra) tolerate the temperature
Skip
- Angelfish — sometimes recommended, but they often outcompete discus for food and carry parasites discus are sensitive to
- Tiger barbs, serpae tetras — fin nippers; the discus’s tall fins are targets
- Most goldfish-temperature cories — won’t survive 84°F long-term
Common problems
Discus going dark or hiding
Stress signal. Check water parameters, tankmates, lighting (sudden bright light stresses discus), recent additions.
Wasting (“thin discus”)
Internal parasites are common in newly imported fish. Hexamita and capillaria are the usual culprits; metronidazole and levamisole treatments resolve most cases when caught early.
Loss of appetite
Almost always water-quality or temperature-related. Test water first, look for tankmate harassment second, suspect disease last.
Plate-fights and missing scales
Pecking-order assertion. Usually self-resolving in a stable group. If a single fish is targeted persistently, that fish should be moved.
Where to buy
Big-box pet stores carry low-quality discus often. Specialist breeders are worth the price difference. Look for:
- Domestic breeders with reputation (Cary Strong, Kenny’s Discus, Wattley Discus, Hans Discus)
- Aquabid auctions from established sellers
- Local clubs and breeders — fewer parasites, easier to inspect before buying
Quarantine every new discus for 4 weeks before adding to an existing group. Treat prophylactically with metronidazole during quarantine.
Bottom line
A group of 6 captive-bred discus in a 90-gallon tank at 84°F with weekly 50% water changes, varied diet, and compatible tankmates is the realistic plan. Budget $400-800 in livestock alone, $1,500+ in equipment. Plan to spend 2-3 hours per week on maintenance for the next 10 years. Done right, the result is the most beautiful freshwater tank in your home.