Heckel Discus
Symphysodon discus
Cichlidae
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About
The Heckel discus is the true Symphysodon discus — the fish Johann Heckel described in 1840, and the one that gave the whole genus its name. It is told apart from the common discus by its barring: three of the nine vertical bars stand out rather than one — the bar through the eye, the fifth or middle bar, and the caudal bar — and it is the heavy fifth bar down the centre of the body that people mean when they call a fish a Heckel. It lives almost exclusively in the blackwater tributaries of the lower Rio Negro, Nhamundá, Trombetas and Abacaxis, where the water is nearly mineral-free (0–1 °dH) and strongly acidic (pH 4.2–6.2) — genuinely softer and more acidic than the pH 5.0–8.0 and 0–12 °dH FishBase publishes for S. aequifasciatus. Nearly every Heckel in the trade is still wild-caught, so it arrives less adaptable than a tank-bred discus and is not the fish to learn discus on.
Care
Not a first discus. Keep 6 or more in a tall 250 L+ tank at 28–30 °C on RO water remineralised to pH 5.0–6.0, GH under 5 °dH and KH under 3 °dH, with frequent large changes using identically prepared water. Dim light, driftwood and leaf litter for tannins; only calm, slow-feeding, soft-water tankmates.
Diet
Omnivore leaning carnivorous. Wild-caught fish often take only live and frozen food at first — bloodworm, brine shrimp, blackworm — and come onto granules slowly. A deliberate, slow feeder that boisterous tankmates will out-compete.
Tankmate compatibility
Gets along with (2)
Possible with care (82)
Avoid (187)
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.
Also in these lists
Frequently asked questions
- What tank size does a Heckel Discus need?
- A Heckel 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 Heckel Discus need?
- Heckel Discus does best at 27–31 °C (80.6–87.8 °F), pH 4.5–7 and a general hardness of 0–5 °dGH.
- What group size does a Heckel Discus need?
- Heckel Discus is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
- Is the Heckel Discus suitable for beginners?
- Heckel Discus is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.