Fungal Infection (Cotton Wool Disease)
Fluffy white or gray cotton-like patches on body, fins, or around mouth. Often secondary to wounds, fin rot, or poor water quality.
Check these symptoms in your tankSymptoms of Fungal Infection (Cotton Wool Disease)
- White cottony patches
- Lethargic / hiding more than usual
- Refusing to eat
- Faded or lost color
How to treat Fungal Infection (Cotton Wool Disease)
- Improve water quality with a 25% water change
- API Pimafix (antifungal) or Seachem Paraguard
- Aquarium salt may help in freshwater tanks
- Remove carbon from filter during treatment
- Treat for 7–10 days
How to prevent it
- Maintain clean water with regular changes
- Treat any injuries or fin damage promptly
- Avoid overcrowding
Conditions with similar symptoms
Bacterial (and sometimes fungal) infection affecting fins and tail. Usually secondary to stress or poor water quality. Fins appear to disintegrate from the edges.
Bacterial infection causing fluid buildup behind the eye, making it protrude. Usually affects one eye. Bilateral pop-eye is more serious and often indicates an internal systemic infection.
Highly contagious bacterial disease. Appears as white/gray patches, often starting at the dorsal area or mouth. Sometimes called "cotton mouth" or "saddleback". Progresses rapidly, fish can die within days.
Not sure? Use the symptom checker
Many fish diseases look alike. Pick the symptoms you see in the free fish disease checker to compare likely causes, or scan a test strip to rule out a water problem first.