Care guide · Freshwater · fish
Heckel discus care guide
Symphysodon discus
The Heckel discus, Symphysodon discus, is a warm-water social cichlid from the Rio Negro region. Despite the broad trade name “discus”, this guide covers one accepted species; aquarium colour varieties do not always prove pure wild ancestry. These fish are social and need a spacious, mature aquarium with stable temperature and excellent water quality. Sources distinguish wild Heckel discus from captive-bred discus in their water chemistry. For captive-bred fish, keep the stable conditions used by the breeder rather than abruptly forcing extremely soft blackwater. Keep ammonia and nitrite at zero, feed small portions and test water routinely.
Plan your aquarium →At a glance
- Temperature
- 28–30 °C
- pH
- 6.0
- GH
- 4–12 °dGH
- Aquarium length
- At least 183 cm
- Minimum aquarium volume
- At least 473 L
- Adult size
- Up to 20 cm
- Group size
- At least 5 individuals
- Temperament
- Peaceful, Territorial
About this species
Symphysodon discus Heckel, 1840 is an accepted species. It is distinct from S. aequifasciatus and S. tarzoo. Many selectively bred colour forms are sold in the trade; a colour label does not establish lineage or geographic origin. The cited species source reports a length of about 20 cm.Natural habitat
Wild fish are associated with the lower Rio Negro and nearby northern Brazilian waters, including Uatumã, Nhamundá, Trombetas and Abacaxis. These blackwater habitats are extremely soft and acidic. Most aquarium fish are captive-bred and may be acclimated to different conditions. Ask about the fish’s current water and provenance; do not mistake a commercial colour form for a confirmed wild locality.Aquarium and layout
OATA recommends about 300 litres for a group of six adult discus, with ample floor space. Provide open swimming room, cover from wood or plants and a calm location without harsh lighting. Use reliable heating and strong filtration. Add fish only to a mature aquarium and test water weekly. OATA recommends a weekly water change of about 50%; adjust maintenance to measured nitrate, stocking and source water. For wild Heckel discus, Aquarist Atlas recommends a footprint of about 183 × 46 cm and roughly 473 litres. OATA gives broader genus-level guidance of about 300 litres for six adult captive-bred discus; this is a different scope and does not replace the more spacious species-specific recommendation used here.Water conditions
Wild Heckel discus and captive-bred discus may need different conditions. Aquarist Atlas describes wild-type fish at about 28–31 °C and pH 4–6 in very soft water. OATA gives genus-level trade care of 26–30 °C, pH 6.0–7.5 and 4–12 °dH. We show 28–30 °C as a cautious temperature overlap. No universal pH or hardness target is given: keep captive-bred fish stable at the breeder’s values and avoid abrupt changes. pH 6 is only the narrow intersection of the two cited ranges, not a precise optimum. The 4–12 °dH hardness range belongs to OATA’s broader captive-discus guidance.Behaviour and group size
Discus are social cichlids; OATA recommends at least five, except for an established pair. They are usually peaceful, but breeding fish may defend a site and dominant individuals can bully weaker ones. Choose companions sparingly, considering behaviour, size and genuinely suitable warm-water needs. No specific species is linked here without an individually verified relationship.Feeding
OATA describes discus as generally carnivorous, eating aquatic invertebrates in the wild. Offer quality complete discus granules or pellets, varied with suitable frozen or live foods. Feed two or three small meals daily and remove leftovers promptly because they can degrade water quality. No exact product with a confirmed current offer is linked.Breeding
Juveniles may be raised together until pairs form. A pair lays eggs on a clean vertical surface and guards them together. After hatching, free-swimming fry temporarily feed on mucus from their parents’ skin. OATA reports hatching in about three days followed by specific fry food; timing depends on conditions. Give the pair quiet, stable water and enough room.Sources & review
This care guide draws on several specialist sources and was last checked on .