Problems, Diseases & Treatments for Discus

Hexamita (*Spironucleus vortens*) is the #1 internal parasite — latent in 80–100% of discus. Classic symptoms: WHITE STRINGY feces (long, transparent, like threads), total refusal of food, weight loss with a HOLLOW belly (sharp spine), isolation, pale colors. Advanced stage: holes on the head (Hole-in-the-Head/HITH). Treatment: METRONIDAZOLE 400 mg/100L in the aquarium, 10 days with a 25% daily water change + redosing. Plus medicated food (1g Metro per 100g beef heart). A temperature of 30–32°C speeds it up. Remove activated carbon (it absorbs it). Treat the ENTIRE aquarium, not just the sick fish.

Ich (*Ichthyophthirius multifiliis*) = white spots like grains of salt (0.5–1mm). Preferred method for discus (no medication): TEMPERATURE 32°C for 10–14 days, raised gradually + salt 1g/L optional + maximum aeration + daily bottom vacuuming. The key to the parasite's cycle: only the 'theront' stage (free-swimming) is treatable; the cycle lasts 3–4 days at 30°C. Continue treatment for 7 days AFTER the spots disappear. For severe cases: JBL Punktol Plus 125 (10ml/40L, 3 days) or eSHa Exit (10ml/50L). A UV sterilizer helps with prevention.

Differentiation is critical — the treatments are opposite! OODINIUM (Velvet): a FINE GOLDEN-BROWN velvety dust spread uniformly (0.05–0.1mm), visible only with an OBLIQUE FLASHLIGHT, aggressively attacks the gills, 80–90% MORTALITY within 5–7 days. Treatment: TOTAL DARKNESS for 7–10 days (the parasite photosynthesizes!) + copper (JBL Oodinol/eSHa Oodinex). ICH: distinct salt-like spots (0.5–1mm) clearly visible, treatable with a 32°C TEMPERATURE. With OODINIUM: do NOT raise the temperature (the parasite tolerates 32°C, but the discus suffocate). Move shrimp/snails/sensitive plants out before using copper.

Columnaris (*Flavobacterium columnare*) = an aggressive bacterium with 50–80% MORTALITY within 24–72h. Symptoms: FLAT WHITISH-YELLOW patches on the mouth, head, gills ('cotton mouth'), inflamed RED edges, rapid spread (hours-days), a lethargic fish. Critical PARADOX: do NOT raise the temperature (as with Ich) — Columnaris ACCELERATES above 28°C! Keep it STABLE at 28–29°C. Urgent treatment: eSHa 2000 (5ml/50L, 5 days) or Waterlife Myxazin or Sera Baktopur Direct (1 tab/20L). Remove carbon. Salt optional 1g/L max 7 days. Telling it apart from Saprolegnia (3D fluffy cotton on old wounds): Columnaris = flat, adherent, yellowish; Saprolegnia = bright white cotton.

EMERGENCY 24–72h! Symptoms: breathing >120/min (normal 60–80), staying at the surface gasping, red inflamed or pale anemic gills, a permanently open operculum, white/grey mucus on the gills. Immediate steps: 1) 30–50% water change with Prime, 2) Test NH3/NO2 (often the cause), 3) Maximum aeration (2 pumps + diffuser), 4) Temperature 30°C. Antibiotic: eSHa 2000 (5ml/50L, 5 days) — top recommendation, or JBL Ektol Bac Plus 250, or Sera Baktopur Direct. Severe cases: Kanamycin (vet prescription) or medicated feeding with an antibiotic in the food. Recovery 2–4 weeks.

3 stages with different treatment. STAGE 1 (whitish, frayed edges): just CLEAN WATER — 30%/day changes for 5 days + 29°C + catappa leaves. No antibiotic. 90% heal on their own. STAGE 2 (red edges, exposed rays): eSHa 2000 (5ml/50L, 5 days) or JBL Ektol Bac Plus 250 or Waterlife Myxazin. Remove carbon. STAGE 3 (melted + ulcers on the body): EMERGENCY — hospital isolation + Sera Baktopur or Kanamycin (vet) + Epsom salt 1g/L + Atvitol. Primary cause: 90% bad water (NO3 >40 ppm) + nipping in the group. Fin regeneration: 2–8 weeks, sped up with 30°C + a rich diet.

Camallanus — red worms visible (0.5–2cm) protruding from the anus, feeding on the fish's blood. They often come from contaminated live food (tubifex) or new fish without quarantine. TREATMENT: Levamisole 1–2 mg/L of water, a 24h bath + 50% change + INTENSIVE bottom VACUUMING (dead worms release eggs). REPEAT after 14 days to catch the new generation. EU products: eSHa NDX (Levamisole + Praziquantel combo), Levamisole HCl powder (~10€/10g). More effective: medicated feeding with Levamisole 0.4g/100g of food, 3 days. For Capillaria (fine white microscopic worms): a similar protocol. Tapeworms (rare): Praziquantel.

DROPSY — it is NOT a disease, it's a SYMPTOM of severe internal failure (internal bacterial infection Aeromonas/Pseudomonas, liver/kidney failure, Mycobacterium, cancer). GUARDED prognosis. Appearance: a balloon-like swollen abdomen, scales raised perpendicular to the body (visible from above = 'pinecone'), bulging eyes, an inflamed vent. Early stage: 30–50% chance with rapid treatment. Advanced stage: <5% — humane euthanasia (clove oil) is the most ethical option. Treatment: hospital isolation + Epsom salt 1–3 g/L + Kanamycin (250mg/40L, 7–10 days) or medicated food with Kanamycin/Oxytetracycline. If several fish at once: suspect Mycobacterium (zoonosis!).

CRUCIAL differentiation — the treatments differ (antifungal vs antibiotic). SAPROLEGNIA (fungi, oomycete): FLUFFY white 3D filaments like COTTON or MOLD, PURE bright white, attacks ONLY dead/injured tissue/non-viable eggs, SLOW spread (days-weeks), edges WITHOUT inflammation. Treatment: Methylene Blue 2 mg/L (safe, under 30 RON at the pharmacy) or JBL Fungol Plus 250 or eSHa 2000 or salt 3g/L in a hospital tank. COLUMNARIS (bacterium): flat adherent WHITISH-YELLOW 2D patches, inflamed RED edges, attacks LIVE tissue (mouth, head), RAPID spread (hours-days). When in DOUBT: treat as Columnaris (it's more dangerous if you're wrong). On breeding eggs: Methylene Blue 1–2 mg/L preventively = the global Stendker/Asian standard.

⚠️ A REAL ZOONOSIS — the only fish disease with RISK TO HUMANS. Mycobacterium marinum/fortuitum/chelonae are acid-fast bacteria present latently in old aquariums. In fish: a CHRONIC INCURABLE DISEASE (5–25% treatment success). The symptom triad: chronic weight loss over MONTHS with no cause + multiple NON-HEALING erosions + deformities (an 'S-shaped' spine, exophthalmia). In HUMANS: 'aquarium granuloma' — a purple/red nodule on a finger/hand 2–4 weeks after contact through SKIN WOUNDS, persists months-years without treatment. Standard solution: HUMANE EUTHANASIA (clove oil 400 mg/L) + TOTAL DISINFECTION of the aquarium (bleach 1:5, 24h + 5 rinses) + discard substrate/plants/décor. MANDATORY PROTECTION: NITRILE gloves for any work in a suspect aquarium! A nodule appears → see a dermatologist urgently.

Probably CONSTIPATION — common and easily treatable. CRUCIAL differentiation: constipation = a SYMMETRICALLY swollen belly + no feces for 2+ days + a normal appetite initially. NOT Hexamita (WHITE STRINGY feces + a HOLLOW belly + total refusal). NOT Dropsy (a HARD belly + RAISED scales). Quick diagnostic test: drop in a cooked, shelled pea — the fish EATS = 95% constipation. Treatment: a MANDATORY 48h fast + EPSOM SALT (magnesium sulfate, NOT table salt!) 1g/L over 2–4 hours + cooked shelled pea 1–2×/day for 3–5 days. Causes: overfeeding (>3 meals/day), floating pellets (swallowing air), lack of fiber. Prevention: 2 meals/day, a fasting day 1×/week, peas weekly, sinking food.

Popeye (exophthalmia) = 4 causes with different prognoses. ONE EYE + an active fish = 95% TRAUMA (hit sharp décor, nipped, jumped). GOOD prognosis 80%. Treatment: Epsom salt 1g/L for 5–7 days (draws out the fluid osmotically) + clean water 30%/day + catappa leaves + Atvitol. Healing 3–4 weeks. BOTH EYES + lethargy = a systemic bacterial INFECTION. Treatment: eSHa 2000 5ml/50L for 5 days + Epsom salt as adjuvant + support. Prognosis 50–70%. BOTH EYES + chronic weight loss + other symptoms = suspect MYCOBACTERIUM (incurable, nitrile gloves!). GAS BUBBLE DISEASE: bubbles under the skin after a large water change with gas-supersaturated water — degas the water + maximum aeration. Recovery 24–72h.

Identify the type: an isolated TRAUMA (décor, nipping) = healing with clean water in 5–10 days, no antibiotic. An ULCER (inflamed red edges, doesn't heal within 7 days, a deepening crater, white mucus): eSHa 2000 5ml/50L for 5 days + Epsom salt 1g/L for 5–7 days + catappa leaves + clean water 30%/day. Severe cases: Sera Baktopur Direct or Kanamycin (vet) + medicated food. NEVER use Betadine/human antiseptics (toxic!). Telling it apart from Columnaris (flat yellowish patches), Saprolegnia (3D cotton), Mycobacterium (multiple chronic non-responsive ulcers). Regeneration support: Atvitol 2×/day for 2 weeks + a high-protein diet + garlic. Permanent scars are possible on ulcers >1cm (cosmetic, the fish stays healthy).

70% of 'imported diseases' = LATENT diseases activated by TRANSPORT STRESS (not new parasites). Chronic cortisol suppresses immunity for 5–14 days → Hexamita (latent in 80–100% of discus!), Ich, Columnaris, Saprolegnia EXPLODE. PREVENTION PROTOCOL: 1) A MANDATORY 4-week quarantine in a separate 80–150L aquarium 2) Temperature 30°C 3) Methylene Blue 1 mg/L (a mild antifungal) 4) Non-iodized salt 1 g/L 5) Atvitol in the food 6) Catappa leaves 1/50L 7) Don't feed for 24h, then 50% food amount for the first 7 days 8) Daily water testing, INTENSIVE monitoring 9) 25–30%/day changes. Prophylactic Metronidazole 200mg/100L for 5 days = only for unknown sources / >4 fish. Stendker / verified breeders = immune support only. Mortality with the correct protocol: <5% (vs 30–50% without).

MINIMUM kit (~50 €): Seachem Prime (~15€) dechlorination/detox, eSHa 2000 (~10€) broad-spectrum antibiotic, eSHa Exit (~10€) anti-Ich, JBL Atvitol (~10€) multivitamins, Epsom salt + aquarium salt (~5€). COMPLETE kit (~100–150 €) adds: Metronidazole (Hexamita), Levamisole/eSHa NDX (worms), Praziquantel/JBL Spirohexol Plus 250 (combo), JBL Punktol Plus 125 (Ich), JBL Oodinol Plus 250 (Velvet), JBL Fungol Plus 250 (fungi), Methylene Blue, Epsom salt, catappa leaves (50 pcs), Seachem Garlic Guard, clove oil (humane euthanasia). Available at: Aquasabi DE, Garnelio DE, RO aquarium shops. Rules: remove carbon before treatment, do NOT mix different antibiotics, do NOT overdose, read the instructions.

3 levels depending on the disease. LIGHT (after a routine treatment, Ich/Hexamita resolved): an 80% water change + deep vacuuming + new activated carbon + 7 days of rest. MEDIUM (Columnaris/Dropsy resolved): remove the fish, empty the water 100%, 5% vinegar on surfaces, décor in boiling water for 10 min, replace 70% of the filter media, cycle for 14 days. COMPLETE (Mycobacterium, mass mortality): euthanize/quarantine the fish for 90 days, DISCARD ALL substrate + plants + porous décor + sponges + media, the aquarium (glass) with BLEACH 1:5 (diluted Domestos) for 24h + 5 consecutive RINSES + double-dose Prime, DRYING 7+ days in the sun, a new cycle 4–6 weeks with starter bacteria (Seachem Stability). For Mycobacterium: nitrile gloves mandatory, splashes of water into a sealed bag → trash (NOT the drain).

9 dark vertical bars on the body, NORMALLY present but temporarily visible under stress. A problem only if they stay dark for over 48h with no cause (new lights, moving, feeding).

Probably a subordinate (bullied). Check whether it eats, stays alone in a top corner, with clamped fins. Solution: rearrange the décor, more discus (dilutes aggression), or temporary separation.

Weeks 1–2: stress, partial refusal of food. Weeks 3–4: hierarchy + colors appearing. Month 2: stable routine. Month 3: fully normal behavior. See the detailed calendar.

If it's temporary (someone walked through the room, lights just turned on): normal, they come back. If it's permanent: test the water immediately, check the temperature, watch the breathing.

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).

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.