Parasites · Updated 2026-09-20
Freshwater ich
A contagious protozoal infection, often called white spot disease, that irritates skin and gills and can spread rapidly through an aquarium.
Signs to watch for
- Salt-like white spots
- Rubbing against objects
- Clamped fins
- Rapid breathing
- Reduced appetite
- Hiding
Causes and risk factors
Ichthyophthirius multifiliis is commonly introduced with infected fish, plants or water. Stress and unstable water quality worsen outbreaks.
How veterinarians diagnose it
Appearance can suggest ich, but microscopy by an aquatic veterinarian or experienced fish-health professional distinguishes it from similar diseases.
Treatment and management
Treat the entire system with a species-safe protocol while correcting ammonia, nitrite, oxygen and temperature. Some medicines are unsafe for invertebrates or scaleless fish.
Prevention
Quarantine new livestock, avoid sharing wet equipment and maintain stable, fully cycled water conditions.
Outlook
Usually good when recognised early; heavy gill infection can kill quickly.