Discus

Wild Discus are native to warm, soft, acidic blackwater rivers and flooded forest habitats of the Amazon Basin, characterised by very warm water (28-32ºC), extremely soft and acidic conditions (pH 5.5-7.0), low mineral content, heavy tannin staining, low current and dense vegetation.

Discus have earned a reputation as one of the most challenging aquarium fish. They are temperature-sensitive, prone to disease under stress, and best maintained in a dedicated setup. They are not recommended for beginner aquarists without considerable preparation. However, in experienced hands with a well-maintained warm soft-water aquarium, Discus are unparalleled in beauty and have a surprisingly personable nature, learning to recognise their keeper.

Discus require water maintained consistently at 28-32ºC with a reliable heater accurate to 0.5ºC. They need soft, slightly acidic water (pH 6.0-7.2; hardness below 15 dGH ideally). In areas with hard tap water, an RO unit or mixing with RO water is often necessary.

Minimum tank: 150-200 litres for a group of six (the recommended minimum group size). Discus tanks are either planted (warm-water species like Amazon sword, Vallisneria, Java fern) or bare-bottom (easier to keep clinically clean). Filtration should provide gentle water movement; a sponge filter combined with a lightly baffled canister filter is common. Water changes of 20-30% are required two to three times per week. All replacement water must be conditioned, heated to tank temperature and pH/hardness-adjusted.

Discus have higher protein requirements than most aquarium fish. The staple diet should be a quality Discus-specific pellet or granule. Supplement generously with frozen bloodworms and frozen or fresh brine shrimp. Many experienced Discus keepers also feed a beef heart mix (finely minced beef heart combined with shrimp, spinach and vitamins), which is highly nutritious and eagerly consumed.

Feed adult Discus two to three times daily; small stomachs favour frequent smaller meals over infrequent large ones. Remove uneaten food promptly. Never feed live tubifex worms, which carry a high risk of bacterial disease. Juvenile Discus require four to five feedings daily. Newly acquired Discus may refuse food; patience and offering live or frozen brine shrimp as an inducement is often necessary.

Discus are display fish appreciated through the aquarium glass. Acclimatisation to hand-feeding, holding food at the water surface and allowing Discus to take it from the fingers, is a rewarding step once fish are fully settled. Transfers should use a large, fine-mesh soft net and minimise time out of water.

They are relatively peaceful within their group. Dominant individuals may bully subordinates at feeding time; providing multiple feeding areas reduces this.

A high-quality, naturalistic aquarium environment provides the most enrichment. In a planted tank, varied species at different heights create a layered environment reflecting the natural blackwater habitat and reducing stress. Driftwood and dried leaf litter provide visual barriers, natural tannins and a naturalistic feel. A varied and consistent feeding schedule creates the recognition behaviour that makes Discus so appealing.

Hexamita / Hole-in-the-head disease: Intestinal flagellate parasites exacerbated by poor water quality; white stringy faeces, lethargy, pitting on the head. Requires veterinary-guided treatment.

White spot (Ich): Treat promptly; particularly dangerous in warm Discus tanks.

Bacterial infections: Often secondary to stress and poor water quality; treat with appropriate antibacterial medication.

Fluke infestations (skin and gill flukes): Common in newly acquired fish; scratching, rapid gill movement, mucus. Treat with aquarium-safe antiparasitic medication.

Nutritional deficiency: Varied diet is essential for health and colouration.