Top 12 Beginner FAQs About Discus Fish with Direct Answers

In Brief

• Discipline and routine matter more than experience: keep the parameters consistent and your discus will thrive.
• A stable temperature of 29°C is essential — fluctuations are more dangerous than a slightly different value.
• Water changes of 30–50% weekly are the foundation of long-term health.
• A minimum of 6 specimens reduces stress and hierarchical aggression.

1. Are discus hard to keep?

They aren't difficult — they just demand consistency, and any disciplined aquarist can keep them successfully. If the tank is fully cycled (4–6 weeks), the temperature is stable, and water changes are done regularly, the risks drop dramatically. → Details: Discus myths — are they really that hard to keep?

2. What tank size is needed?

The absolute minimum for 5–6 adults is 200 litres. A 300–400 litre tank is easier to manage: it dilutes nitrates, buffers temperature swings, and reduces territorial conflict. → Details: Discus aquarium size

3. How many discus can I keep?

A minimum of 5–6 specimens — smaller groups lead to excessive dominance and frequent illness. In a 400-litre tank you can comfortably keep 8–10 adults. → Details: How many discus in an aquarium?

4. What is the ideal temperature?

29°C — below 27°C the immune system weakens quickly. Sudden swings of more than 1–2°C are more dangerous than a slightly elevated temperature. → Details: Ideal discus temperature

5. Is tap water in Romania safe?

Generally yes — approximately 80% of urban water supplies provide compatible water after dechlorination. Target parameters: pH 6.5–7.5 and TDS 100–250 ppm. Dechlorination is mandatory before every water change. → Details: Water parameters for beginners

6. How often should the water be changed?

30–50% weekly, without exception — no filtration system can compensate for a lack of fresh water. Nitrates above 20–30 ppm slowly degrade discus health. → Details: Water changes for beginners

7. What should I feed them?

2–3 meals per day: properly prepared beef heart, frozen brine shrimp, and discus-specific granules. If they haven't eaten everything within 3 minutes, you've fed too much — leftover food pollutes the water quickly. → Details: Feeding discus for beginners

8. What are the monthly running costs?

Moderate and predictable: the main expenses are food, electricity (a 50–100 W heater running continuously), and water treatment products. Real savings come from prevention, not from cutting corners on equipment quality. → Details: Monthly cost of keeping a discus aquarium

9. What other fish can I keep with discus?

Ideal tank mates: Cardinal Tetras, Corydoras Sterbai, and South American tetras that tolerate 29°C. Avoid aggressive species, fast-moving fish, and any species that prefers temperatures below 26°C. → Details: Best discus tank mates

10. Why are my discus turning dark or hiding?

Darkening and hiding are warning signs — stress, incorrect parameters, or the onset of disease. Test nitrates, pH, and temperature immediately, then check for an aggressor or external stress sources (noise, vibrations, excessive light). → Details: Why is my discus turning black?

11. How long do they live, and how big do they get?

12–18 cm in diameter, with a lifespan of 10–15 years — a long-term commitment. Full growth takes 12–18 months; optimal conditions and frequent feeding ensure maximum size and the most vivid colours. → Details: Why keep discus?

12. What should I check when buying?

Only buy active specimens with a round body, proportionate eyes, and open fins, that will eat in front of you. Avoid fish sitting at the bottom or in a corner, with dark colouration, a pinched forehead, or disproportionately large eyes. Quarantine them before introducing them to other fish. → Details: How to choose a healthy discus

Key Values at a Glance

Further Reading

• Myths: are discus hard to keep?
• Water parameters for beginners
• Feeding discus for beginners
• Monthly cost of a discus aquarium
• How to choose a healthy discus