What tank size does a Discus need?

A Discus needs an aquarium of at least 250 litres (66 US gallons) with a footprint at least 120 cm (47.2 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Discus need?

Discus does best at 27–31 °C (80.6–87.8 °F), pH 5.5–7.5 and a general hardness of 1–12 °dGH.

What group size does a Discus need?

Discus is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Discus suitable for beginners?

Discus is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Species library

Discus

Symphysodon aequifasciatus

Cichlidae

FishDifficulty: ●●●●●Data: well-established

📷 H. Zell · CC-BY-SA-3.0 · resized · Wikimedia Commons

Discus — Symphysodon aequifasciatus — 📷 H. Zell · CC-BY-SA-3.0 · resized · Wikimedia Commons

About

The discus is the celebrated 'king of the aquarium', a laterally compressed, almost circular cichlid from the slow, warm blackwater tributaries of the Amazon basin. Its disc-shaped body is as tall as it is long, so it needs vertical swimming room as much as floor space, and it demands very warm, soft, acidic and spotlessly clean water. Discus are peaceful but shy and form dominance hierarchies, so they are kept in groups of six or more to spread out any bullying.

Care

Provide a tall, roomy tank (250 L+, around 50 cm high) with very warm (28-30 C), soft, acidic water kept pristine through frequent large water changes. Keep a group of 6 or more and pair only with calm, slow-feeding tankmates; avoid boisterous or fin-nipping fish.

Diet

Omnivore leaning carnivorous and a slow, deliberate feeder that is easily out-competed. Feed frozen bloodworms, brine shrimp and blackworms plus quality granules in small, frequent meals, and choose gentle companions.

Tankmate compatibility

Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.

Telling males from females

What works for this species, most reliable first.

Extended finsStrong · from about 8 months, and later in a suppressed male
On many cichlids and killifish the male's dorsal and anal fins draw out into trailing points as he matures, while the female's stay rounded.
VentingA hint only · only on a mature fish, easiest when she is in breeding condition
The method breeders use when the answer has to be right. Hold the fish upside down in a wet hand or soft net and look at the two openings ahead of the anal fin. The forward one is the anus; the one behind it is what you are reading.
Adult sizeA hint only · only across animals of the same age
In many cichlids, catfish and loaches one sex simply grows larger — usually the male, though there are well-known reversals.

All the methods, with diagrams

Also in these lists

Peaceful community fish

Frequently asked questions

What tank size does a Discus need?: A Discus needs an aquarium of at least 250 litres (66 US gallons) with a footprint at least 120 cm (47.2 in) long — for this species, swimming length matters as much as raw volume.
What water parameters does a Discus need?: Discus does best at 27–31 °C (80.6–87.8 °F), pH 5.5–7.5 and a general hardness of 1–12 °dGH.
What group size does a Discus need?: Discus is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
Is the Discus suitable for beginners?: Discus is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

Water & tank

Temperature27–31°C

Optimal temp.28–30°C

pH5.5–7.5

Hardness (GH)1–12°d

Carbonate (KH)0–6°d

Adult size18 cm

Min. volume≥ 250 L

Min. tank length≥ 120 cm

Group size≥ 6

Swimming zoneMid

TemperamentPeaceful

Water typeFreshwater

FlowLow

Lifespan~12 yrs

Try in the calculator