The Golden Rule: Test Water First
Ninety percent of betta disease cases trace back to poor water quality. Before reaching for medication, test your water. A liquid test kit (API Master Kit) measures ammonia, nitrite, nitrate, and pH. If ammonia reads above 0 ppm or nitrite above 0 ppm, your tank is causing the illness — no medication will overcome poison in the water.
Perform an immediate 30-50% water change with properly dechlorinated water at the correct temperature. In many cases, clean water alone resolves early-stage diseases within 3-5 days. Medication treats symptoms; clean water heals the fish.
Fin Rot — Most Common Betta Disease
Symptoms: fin edges appear ragged, torn, or as if chewed. May have a dark edge (bacterial) or white fuzzy growth (combined bacterial-fungal). Fish behavior may be normal in mild cases. Severe fin rot reaches the body.
Cause: poor water quality, low temperature, stress. Almost never happens in well-maintained tanks.
Treatment — mild: 30% water change daily for 5 days, raise temperature to 28°C, add aquarium salt 1 teaspoon per 4 liters. Monitor improvement. Treatment — moderate to severe: add API Furan-2 or Seachem KanaPlex alongside clean water protocol. Full 7-day antibiotic course required. Remove carbon from filter during treatment.
Recovery: fin tissue regrows approximately 1-2mm per week in perfect water. New growth is initially clear/pale, gradually darkens to match original coloring.
- ✦Do not confuse fin rot with fin tears from sharp décor — inspect décor for rough edges
- ✦Fin regrowth after rot is never exactly as it was — prevention is far better than cure
Ich (White Spot Disease)
Symptoms: tiny white dots on fins and body, like salt grains. Fish may flash (rub against objects) and clamp fins. Breathing becomes labored when gills are affected.
Cause: the parasite Ichthyophthirius multifiliis. Very contagious. In Cambodia, often arrives with new fish from crowded market conditions. Rainy-season temperature swings also trigger outbreaks in existing tanks.
Treatment: raise temperature gradually to 30°C (1°C per 12 hours — sudden changes kill the fish). Add aquarium salt 1 tablespoon per 4 liters. Dose API Super Ick Cure or Seachem Paraguard. Treat for 10-14 days past last visible spot — the medication only kills the free-swimming stage, not the dots on the fish.
All fish in the tank must be treated simultaneously — ich spreads through shared water. Remove invertebrates (shrimp, snails) during treatment if using copper-based medications.
Velvet (Gold Dust Disease)
Symptoms: fine gold or rust-colored dust on body, especially visible under flashlight in a dark room. Rapid gill movement, clamped fins, lethargy. One of the fastest-killing betta parasites.
Cause: Oodinium (a dinoflagellate parasite). Light-sensitive — reproduces faster under bright light.
Treatment: immediate darkening of the tank (cover with black towel, 24 hours/day during treatment). Raise temperature to 30°C gradually. Copper-based medication (Cupramine, API General Cure) for 10-14 days. Add aquarium salt. Keep lights OFF.
Critical: velvet can wipe out an entire tank in 5-7 days. Once gills are coated, survival rate drops sharply. Treat aggressively from first symptom.
Columnaris (Cotton Mouth / Saddle Back)
Symptoms: white or gray patches on head, back, or mouth. Looks like cotton or mold. Saddle-shaped patch near dorsal fin is classic presentation. Fish deteriorates rapidly — often fatal within 72 hours if untreated.
Cause: bacterial infection, Flavobacterium columnare. Associated with warm water (above 28°C) and poor water quality — particularly problematic in Cambodia's hot season.
Treatment: immediate broad-spectrum antibiotic (Furan-2, Kanaplex). Lower temperature slightly if above 30°C. Salt 1 tablespoon per 4 liters. Clean water mandatory. Columnaris moves fast — start treatment same day symptoms appear.
- ✦Columnaris is highly contagious — quarantine infected fish immediately
- ✦Increase water change frequency to daily during columnaris outbreak
Constipation and Swim Bladder Disorder
Symptoms: bloated belly, difficulty maintaining depth, floating at top or sinking to bottom, curved spine posture. Often confused with dropsy but crucially there are no protruding scales.
Cause: overfeeding, poor-quality food, internal parasites (in chronic cases).
Treatment: fast the betta for 2-3 days. No food at all. Then offer one or two daphnia (the best natural laxative for bettas) or a small piece of cooked, deshelled green pea. Maintain pristine water during recovery.
Daphnia are available fresh in Cambodian fish markets and are the single most effective treatment for betta constipation. Green peas work equally well — cook briefly, remove shell, offer a pea-sized piece. Most swim bladder cases caused by constipation resolve in 3-5 days.