Natural Habitat & Origin
Discus are native to the Amazon River basin, particularly the blackwater and clearwater tributaries in Brazil, Peru, and Colombia. They inhabit warm, soft, acidic water among submerged roots and fallen trees. Wild discus are more muted in color than captive-bred strains, which have been selectively bred for decades to produce brilliant reds, blues, turquoise, pigeon blood, and checkerboard patterns.
Why Discus Are an Advanced Fish
Discus are demanding for several reasons:
- Temperature: They require 82–88°F — significantly warmer than most tropical fish
- Water quality: Extremely sensitive to ammonia, nitrite, and nitrate. Many keepers perform daily 50% water changes.
- Diet: Picky eaters that need high-protein foods, often multiple feedings per day
- Stress sensitivity: Stressed discus turn dark, stop eating, and are susceptible to disease
- Cost: Quality discus cost $30–$150+ each, and you need at least 5
Tank Setup
- Tank size: 55 gallons for 5 discus, 75+ for 6–8. Taller tanks are preferred since discus are vertically oriented.
- Temperature: 82–88°F — a reliable heater (or two for redundancy) is critical
- Substrate: Many serious discus keepers use bare-bottom tanks for easier cleaning. If using substrate, fine sand is preferred.
- Filtration: Heavy filtration — canister filters rated for 2–3x the tank volume
- Plants: Optional but beautiful. Choose heat-tolerant species: anubias, java fern, amazon swords, vallisneria. Avoid CO2-dependent plants unless you're experienced.
- Driftwood: Releases tannins that help acidify and soften water naturally
- Lighting: Moderate — avoid harsh, direct light
Water Parameters
- Temperature: 82–88°F (28–31°C) — non-negotiable
- pH: 5.5–7.0 (soft, acidic water)
- GH: 1–4 dGH (very soft)
- Ammonia/Nitrite: 0 ppm (absolutely zero tolerance)
- Nitrate: below 10 ppm (ideally below 5 ppm)
- TDS: 50–150 ppm
Water changes are the most critical aspect of discus keeping. Many experienced keepers perform 50% daily water changes for growing juveniles and 30–50% water changes 3–5 times per week for adults. RO/DI water or remineralized RO water is often necessary depending on your tap water.
Diet & Feeding
- Juveniles: Feed 5–6 times per day with high-protein foods to promote growth. Frozen bloodworms, beef heart mix, and Hikari Discus Bio-Gold are staples.
- Adults: Feed 2–3 times per day. Varied diet of frozen bloodworms, brine shrimp, high-protein pellets, and occasional beef heart.
- Avoid: Tubifex worms (parasite risk), low-quality flakes
Discus are slow, deliberate eaters. Ensure they get food before faster tank mates consume it all. Remove uneaten food promptly — it fouls water quickly at discus temperatures.
Popular Varieties
- Blue Diamond: Solid metallic blue. One of the most popular strains.
- Pigeon Blood: White/cream body with red spots and markings
- Turquoise: Blue-green base with red/brown striations
- Red Melon: Solid orange-red, highly sought after
- Checkerboard: Red and blue checkerboard pattern
- Snakeskin: Fine spotted/striped pattern
- Wild-caught: Heckel, brown, green, and blue wild forms. More demanding but rewarding for experienced keepers.
Tank Mates
The warm temperature requirement limits compatible species:
- Best: Cardinal tetras, rummy nose tetras (both tolerate warm water and look stunning with discus)
- Good: Sterbai corydoras (heat-tolerant cory species), bristlenose plecos, otocinclus
- Shrimp: Amano shrimp and cherry shrimp can work but may be eaten by large discus
- Avoid: Any aggressive or fast-moving species that will outcompete discus for food, plus anything that requires cooler water
Common Diseases
- Hexamita (hole-in-the-head): Pitting/lesions on the head. Caused by internal parasites exacerbated by stress and poor water quality. Treat with metronidazole.
- Gill flukes: Rapid breathing, scratching on surfaces. Treat with praziquantel.
- Internal parasites: Common in wild-caught and imported discus. Prophylactic deworming with General Cure is recommended for new arrivals.
- Stress darkening: Discus turn dark brown/black when stressed. Identify and remove the stressor (water quality, aggression, illness).
Frequently Asked Questions
Are discus hard to keep?
Yes. They are one of the most demanding freshwater fish. They require pristine water, warm temperatures, frequent feedings, and a stress-free environment. They are not recommended for anyone who hasn't successfully kept other tropical fish for at least a year.
How many discus should I keep?
At least 5. Discus are social and establish hierarchies. Groups smaller than 5 result in excessive bullying of the lowest-ranked fish. Odd numbers (5, 7) tend to distribute aggression better than even numbers.
Can I keep discus in a planted tank?
Yes, but it's challenging. The high temperature (84–86°F) limits plant choices and accelerates algae growth. Low-tech plants like anubias, java fern, and amazon swords do well. Avoid high-demand plants that need CO2 and intense lighting unless you're very experienced.