Discus Aquarium Setup

Minimum 200L for 5–6 discus. 250–300L recommended for a healthy group with room for hierarchy. Below 150L = chronic stress, high mortality.

An external filter with a flow rate of 4–6× the volume/h. For 250L → 1000–1500 L/h. Trusted brands: Eheim Classic 600, Fluval 307, JBL CristalProfi e1502. Avoid small internal filters.

Cycling = growing the beneficial bacteria that turn toxic ammonia into nitrite, then into less dangerous nitrate. It takes 4–6 weeks. Without it, discus die within 48–72h from poisoning.

Ask for filter sponges from a breeder with a mature aquarium — a ready-made bacterial colony, cycling in 3–7 days. Or use Seachem Stability/Tetra SafeStart according to the instructions.

For beginners: bare-bottom (no substrate) is easier to clean and lets you spot health problems. Fine sand substrate (0.5–1mm, max 3cm layer) is fine for aesthetics, but needs weekly vacuuming. Avoid gravel — it traps waste.

The rule is 1W/liter (1.2W/L in winter). For 200L → 200W total, ideally 2 heaters of 100W (safety against failures). Trusted brands: Eheim Jäger, Aquael Comfort Zone, JBL ProTemp, Fluval E. Add an external Inkbird thermostat for ±0.2°C precision.

Power of 0.3–0.5 W/L for a moderately planted tank, 6500K full spectrum, 8–10 hours/day with a mandatory timer. RO 2026 models: Chihiros A2 Plus (350–550 RON), Aquael Leddy Slim Plant (250–450 RON), Twinstar S-Line premium (800–1200 RON). Discus prefer diffuse light.

Top 4 'set-and-forget' plants: Anubias (any variety, on driftwood), Microsorum pteropus (Java Fern), Cryptocoryne wendtii, Ceratophyllum demersum (floating). All tolerate 30°C, need no CO2, low light. Avoid Glossostigma, HC Cuba, Cabomba — they die above 26°C.

Below 300L → external filter (Eheim, Fluval, JBL, 300–1500 RON, plug & play). Above 400L → a sump becomes feasible (1500–5000 RON, more filter volume, hides equipment). Beginners and locations sensitive to flooding: the external filter is always the safe choice.

1 Terminalia catappa leaf per 30L of water (200L → 6–8 leaves). Add gradually, 2–3/week, to avoid a sudden pH drop. Benefits: antibacterial tannins, natural pH 6.0–6.5, reduced stress, encourages breeding. Replace every 3–4 weeks.

Temperature 29–30°C, ammonia 0 ppm, nitrite 0 ppm, nitrate below 20 ppm, pH 6.0–7.5 (stability > exact value). KH ≥2 dKH (avoid pH crash). GH 3–8 dGH.

Below 28°C the discus immune system collapses → Hexamita (internal parasites) and Ich (white spot) within 1–2 weeks. The high temperature is the definition of the species, not optional.

A liquid kit is mandatory (API Master Test Kit or JBL Test, NOT strips — ±20% error). Test ammonia + nitrite daily during cycling, then weekly. KH/GH monthly.

Yes in about 80% of cases, but always test your own supply first — tap water varies enormously by region. A dechlorinator is mandatory (chloramine does NOT evaporate). Hard tap water (TDS 400+) → a 40-50% RO mix is recommended; soft tap water (TDS under 250) is often fine directly. Always dechlorinate (Seachem Prime).

It depends on your tap water. Very hard supply (TDS 400+) → YES, a home RO unit usually pays for itself within 3-6 months. Moderately soft supply → buying RO water by the bottle is often cheaper. For breeding → effectively MANDATORY. A small hobbyist with one tank → buy RO water rather than installing a unit.

NO! Pure RO water (TDS 0, KH 0) = guaranteed pH crash. Mandatory: mix it with tap water (50/50 Bucharest) OR remineralize with Seachem Equilibrium + baking soda. RO water with no minerals = death within 24h.

A sudden drop >1.0 pH within a few hours, fatal in 24–48h. It happens when KH is below 1 dKH — the water no longer buffers the acids from respiration. Prevention: KH minimum 2 dKH AT ALL TIMES, monthly testing, baking soda on hand (0.5g/10L = +1 dKH). 100% unmineralized RO water = the #1 cause.

3 safe methods: 1) RO water mixed 50/50 with tap (Bucharest) — the most stable. 2) Aquarium peat in the filter (JBL Tormec ~50g/100L) — lowers it gradually 0.3–0.8. 3) Catappa leaves + mopani wood — a 0.2–0.5 drop. Do NOT use chemical 'pH down' — it causes shocks and a pH crash when you stop.

EMERGENCY: 1) 50% water change immediately with dechlorinated water at 29°C. 2) Seachem Prime double dose (5ml/100L) — neutralizes NH₃+NO₂ for 24-48h. 3) Turn on extra aeration. 4) Stop feeding for 48h. 5) Test again in 2 hours. Causes: filter cleaned in tap water, overpopulation, incomplete cycling.

Keeping Stendker/locals: 100–200 ppm. Breeding: 50–100 ppm. Wild (Heckel, Altum): below 50 ppm. Measure with a digital TDS meter (HM Digital TDS-3 ~60 RON, reliable for 3-5 years). Calibrate 1×/year with 342 ppm solution. Strips do NOT measure TDS correctly.

Yes, but only for advanced keepers (NOT beginners). Strict rules: KH minimum 3–4 dKH, a solenoid on a timer (off at night), extra aeration at night, weekly pH monitoring. A complete JBL/Aquario system 300-500 €. For 90% of keepers: low-tech without CO2 is the correct choice with Anubias/Java Fern/Echinodorus plants.

2–3 changes/week, 25–30% each. For fry: 50% daily. Don't change all the water at once. Use dechlorinated water at the aquarium temperature ±1°C.

Adults: 2 meals/day. Juveniles (under 10 cm): 3 meals/day. Fry: 4–5 meals/day. The 3-minute rule — as much as they eat without it falling to the bottom. One fasting day per week is recommended.

Beginners: premium discus pellets (Sera Discus, Tetra Discus) + frozen brine shrimp + frozen bloodworms. Avoid live food (parasite risk) and homemade beef heart in the first year (complicated).

The first 3 days after bringing them home = NORMAL. Over 5 days = a problem. Check: temperature 29°C? ammonia/nitrite = 0? bullying? Change the type of food, try frozen. Don't insist with large amounts.

Top 5 killers: an uncycled aquarium (70%), temperature below 28°C (50%), an undersized filter (40%), cheap sick fish (60%), preventive treatments without a diagnosis (30%).

The first year: discus ONLY. After 1 year, options: Corydoras sterbai, cardinal tetra (careful — they can be eaten). NEVER: angelfish (parasites), barbs (nip), guppies (different requirements).

NO. Treatments with no symptom = they destroy the filter's bacterial colony → ammonia crisis. Treat only based on confirmed symptoms. At the first sign: test the water (90% of 'diseases' are bad parameters).

Common invisible causes: ammonia below 0.25 ppm (undetectable with strips), temperature dropping at night, old oxidized food, a bad source (fish already sick at purchase).