DISCUS BLUE COBALT 3.5 INCH

Cobalt discus: a flattened jewel of the Amazon, watching from warm shadows.

Buy premium Blue Cobalt Discus, 3.5 inch, for your planted Amazon biotope. Hardy sub-adults with vivid blue colour — expert care guide included.

• Water Conditions: The Blue Cobalt Discus is a warm-water Amazonian cichlid, so stable, soft, slightly acidic water is essential. Aim for a temperature of 28–30°C (82–86°F); many breeders keep juveniles at the upper end of this range (29–30°C) to encourage steady growth and a strong appetite, then drop to 28–29°C for adults. pH should sit between 6.0 and 7.0, with 6.2–6.8 being the sweet spot — but remember that a rock-steady pH is far more important than chasing a specific number. General hardness of 1–8 dGH (soft) and carbonate hardness of 1–4 dKH suit them well, with a TDS of roughly 80–180 ppm. Ammonia and nitrite must always read zero, and nitrate should be kept below 20 ppm, ideally under 10 ppm. This means generous weekly water changes of 30–50% using pre-heated, aged, dechlorinated water matched to tank temperature. If your tap water is hard or high in nitrate, mix it with RO/DI water and remineralise to the values above. Peat filtration, Indian almond leaves and driftwood all help create the gentle tannin-rich conditions discus love, while gentle flow and excellent oxygenation keep them comfortable without buffeting these deep-bodied swimmers.
• Tank Setup and Housing: Although a 3.5 inch Blue Cobalt looks small on arrival, it will grow to roughly 15–20 cm (6–8 inches) over the next 12–18 months, so plan for the adult size. A group of six or more is strongly recommended because discus are social shoaling cichlids; keeping one or two alone often leads to a shy, stressed, hiding fish. Allow a minimum of 55–75 gallons (around 250–300 litres) for a group of six, with a taller tank of at least 50–60 cm height being ideal. Use fine sand or a bare-bottom setup for juveniles — bare bottoms are easier to keep spotlessly clean, while sand looks natural and lets them sift. Furnish with driftwood, Amazon swords, vallisneria and floating plants to diffuse light, as discus dislike bright, harsh illumination. Provide dim, subdued lighting, a quiet filter such as a mature canister plus a sponge filter, and no sharp rocks or ornaments that could injure their flanks. Always fit a tight lid — discus can and do jump when startled.
• Suitable Tank Mates: Blue Cobalt Discus are peaceful, slow-moving cichlids that do best with calm, warm-water companions that will not nip fins or outcompete them at feeding time. Excellent choices include cardinal tetras, rummy-nose tetras, lemon tetras, black neon tetras, marbled hatchetfish and pencilfish, all of which add movement and act as dither fish, helping shy discus feel secure enough to swim in the open. Warm-water Corydoras such as Corydoras sterbai, C. adolfoi and C. duplicareus are ideal bottom-dwellers, and small plecos like the bristlenose are usually fine — though avoid the common pleco, which can grow huge and may graze on discus slime coats if underfed. German blue rams can work in a spacious, well-maintained tank. What to avoid: fin-nippers such as tiger barbs and serpae tetras; boisterous or aggressive cichlids like convicts, jack dempseys or red devils; large predatory fish such as oscars; and cold-water species like goldfish. Angelfish are sometimes kept with discus but can carry diseases and compete at feeding time, so they are a riskier pairing. As a rule, keep discus in groups of six or more of their own kind, and add tank mates that enjoy the same 28–30°C water — many tropical fish simply cannot tolerate it long-term.
• Feeding Habits: Discus are omnivores that lean heavily towards protein, and juveniles especially need frequent, high-quality meals to grow into round, deep-bodied adults. Feed 3–4 small meals a day while they are young, dropping to 2–3 feeds a day as they mature, and offer only as much as they clear in a few minutes. A varied diet should include quality discus pellets or granules as the staple, plus frozen and live foods such as bloodworm, blackworm, mysis shrimp, brine shrimp and krill. Beef heart mixes are popular for conditioning and growth but are rich and messy, so use them sparingly — particularly with adults, where overuse can lead to fatty liver and water quality problems. Soak freeze-dried foods briefly before feeding to prevent bloating, and avoid live tubifex worms, which can introduce parasites. Discus are deliberate, almost picky eaters and can be intimidated by fast, greedy tank mates, so feed at the same spot each time and watch that every fish gets its share. Remove uneaten food after 10–15 minutes, and consider a garlic or vitamin soak to tempt new arrivals and support immunity.
• Care and Maintenance: These 3.5 inch Blue Cobalts are sub-adults — past the delicate fry stage but still deserving of careful husbandry. Quarantine all new arrivals for 4–6 weeks before adding them to a display tank, and acclimatise by drip method over 45–60 minutes to avoid pH and temperature shock. Keep them in groups of six or more to spread any aggression and let a natural pecking order form, and remember that discus kept alone often become withdrawn. Perform weekly 30–50% water changes with temperature-matched, dechlorinated water, siphon the substrate thoroughly, and rinse filter media in tank water only to protect your beneficial bacteria. Watch daily for warning signs: white, stringy faeces, dark colouration, clamped fins, hiding or loss of appetite can indicate hexamita or internal parasites, while scratching and rapid gill movement may point to gill flukes or poor water quality. Because discus are prone to these issues, a dedicated quarantine or hospital tank and an early treatment plan are worth having on standby. Keep stress low — avoid sudden temperature swings, loud vibrations and unnecessary netting. With stable warm water, a varied diet and a peaceful community, your Blue Cobalt Discus should live for many years, growing into a stunning, deep-blue centrepiece for your Amazon biotope.