Columnaris is a freshwater bacterial infection (Flavobacterium columnare) that produces white or grey patches on the body. Aggressive and fast-spreading; often confused with fungus.
Stress, poor water quality, temperature swings, or introduction of infected fish. Often appears after a tank crash or ammonia spike.
Multiple effective treatments exist. Pick based on your tank type, livestock sensitivity, and severity. Always treat in a separate quarantine/hospital tank - most medications are toxic to coral, invertebrates, and live rock biology.
Avoid stress (overcrowding, sudden parameter changes). Quarantine new fish.
White or grey cottony patches on body. Saddle-shaped lesions on the back. Mouth fungus appearance.
Stress, poor water quality, temperature swings, or introduction of infected fish. Often appears after a tank crash or ammonia spike.
Kanaplex: Most effective treatment: full course in hospital tank, 7-10 days. Combine with daily 25% water changes.
Avoid stress (overcrowding, sudden parameter changes). Quarantine new fish.
High - aggressive variant kills within 48 hours
Always treat in a separate quarantine or hospital tank. Most medications are toxic to coral, invertebrates, and live rock biology.
Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.