The Foundation of All Betta Disease Treatment
Before reaching for any medication, perform an emergency water change of 25-30%. The majority of betta diseases are caused or worsened by poor water quality — elevated ammonia, nitrite, or nitrate, incorrect temperature, or accumulated organic waste. A clean environment is both prevention and the foundation of every treatment protocol.
Set up a quarantine tank (hospital tank) before treatment whenever possible. A small 5-liter container with a sponge filter and heater keeps medication concentrated, prevents cross-contamination, and allows you to monitor the sick fish closely. Treat in the hospital tank, not the display tank.
Temperature matters critically during treatment. Betta immune function peaks at 78-80°F (26-27°C). If your tank runs cooler — common in Cambodia during rainy season when ambient temperature drops — raise the temperature slowly by 1°C per hour to the target range.
Fin Rot — Most Common Betta Disease
Fin rot is the most frequently seen betta disease and the easiest to treat when caught early. Symptoms begin as fraying or darkening of the fin edges, progressing to significant fin loss and eventually reaching the body (body rot) if left untreated. The cause is almost always bacterial — Pseudomonas and Aeromonas species that proliferate in poor water conditions.
Mild fin rot (light fraying, no discoloration) often resolves with clean water alone: perform 25% water changes every other day for two weeks and ensure temperature stays at 28°C. For moderate to severe fin rot (significant loss, black edges, redness), add aquarium salt at 1 tablespoon per 10 liters and treat with a broad-spectrum antibiotic like Kanaplex or API Fin and Body Cure. Continue treatment for the full recommended course — stopping early causes relapse.
Do not confuse fin rot with "fin biting," where the betta bites its own fins out of boredom. Fin biting shows clean, sharp bite marks with no discoloration or fuzzy edges. The fix is environmental enrichment — more plants, a larger space, a mirror for short supervised interactions.
- ✦Daily water changes of 20% during antibiotic treatment maintain drug efficacy
- ✦Remove activated carbon from filters during medication — it absorbs the drugs
- ✦Salt dose: 1 tablespoon (5g) per 10 liters — not more for bettas
- ✦New fins grow back pale/transparent then regain color over weeks
Velvet (Oodinium) — The Invisible Killer
Velvet is caused by a parasitic dinoflagellate (Oodinium pilularis) that attaches to the fish's skin and gills. It presents as a golden, rust, or velvety dust coating under direct light — shine a flashlight at a low angle across the fish to see it clearly. Infected fish scratch against objects, clamp fins, breathe rapidly, and lose appetite. Velvet progresses rapidly and can kill a fish within days.
Treatment: darken the tank completely (cover with a towel) for 4-5 days — Oodinium cysts require light to complete their life cycle. Simultaneously treat with copper-based medication (Cupramine or SeaCure) at the manufacturer's dose. Raise temperature to 30°C to accelerate the parasite life cycle, exposing the vulnerable free-swimming stage to the medication. Treat for the full 14 days even if the fish appears cured — encysted parasites are drug-resistant.
Velvet is highly contagious. If you see it in one tank, assume all connected tanks and any shared equipment are contaminated. Quarantine everything, disinfect nets in a saltwater solution before reuse, and treat all affected tanks simultaneously.
White Spot (Ich) — Cryptocaryon irritans
Ich presents as small white dots resembling grains of salt scattered across the fins and body. The fish will scratch against objects (called "flashing") and may show rapid breathing. Ich is extremely common in fish stressed by temperature fluctuation — a sudden drop of even 2-3°C can trigger an outbreak in a fish that was previously a healthy carrier.
Raise temperature to 30°C gradually over 24 hours. The heat accelerates the Ich life cycle, forcing parasites out of their protective cysts and into the free-swimming stage where medication can kill them. Treat with Ich-X, Malachite Green, or API Super Ick Cure for 10-14 days. Perform 25% water changes every other day before re-dosing to maintain drug concentration.
In Cambodia's climate, Ich outbreaks peak during the cool season (November-January) when temperatures fluctuate and when air conditioning is running constantly in urban apartments. Using a thermometer and maintaining a stable 27-28°C prevents most Ich outbreaks entirely.
Popeye, Dropsy, and Bloat
Popeye (exophthalmia) is a bacterial infection of the eye socket causing one or both eyes to protrude. It is usually secondary to another infection or injury. Treat with Kanaplex in the food or water for 10 days. One-sided popeye has a good prognosis; bilateral popeye is more serious and may indicate systemic infection.
Dropsy is not a disease but a symptom — fluid accumulation causing the fish to bloat and the scales to pinecone outward. It indicates kidney failure, usually from a severe bacterial infection. Dropsy with full pineconing is very difficult to reverse. Treatment involves Epsom salt baths (1 teaspoon per 5 liters, 15-minute baths twice daily) to draw excess fluid out, plus systemic antibiotics (Kanaplex or Furan-2). Begin treatment immediately at the first sign of swelling before full pineconing develops.
Bloat (constipation or internal parasites) causes a rounded belly without the pineconing of dropsy. Fast the fish for 3 days, then feed a small piece of deshelled, blanched pea to act as a laxative. If bloat persists beyond a week or the fish swims with difficulty, treat with Metronidazole (Flagyl) for internal parasites.
Prevention Is the Best Medicine
The single most effective disease prevention protocol for betta fish in Cambodia is a weekly 25-30% water change combined with a stable temperature between 27-29°C. Stress is the root cause of 90% of all betta diseases — stress suppresses the immune system, allowing opportunistic bacteria and parasites to flourish.
Never introduce new fish, plants, or decor without quarantine. New fish should spend 2-4 weeks in a separate quarantine tank before joining any established aquarium. Plants from shops can carry snails, parasites, and disease — rinse in a diluted potassium permanganate solution (1 crystal per liter for 10 minutes) before planting.
Maintain a small medicine cabinet: aquarium salt, a broad-spectrum antibiotic (Kanaplex), a copper-based parasite treatment (Cupramine), Ich medication, and Metronidazole. Early treatment dramatically improves outcomes — a disease caught in day one is almost always curable; one that has progressed for two weeks often is not.