Things You'll Need
- Freshwater aquarium
- Large aquarium net
- Pond heater
- Live food
Instructions
Quarantine the affected fish, if only a few individuals are exhibiting symptoms. Move to a freshwater aquarium or another pond.
Remove any leeches with a net from the original pond and from the fish. Leeches might pass on infections.
Keep the infected fish reasonably warm, at around 68-75 degrees Fahrenheit. If the koi start showing symptoms during or just before the winter, consider taking them inside or installing a pond heater.
Feed all your koi a high-quality diet with supplemental live food such as blood worms. This improves their condition and helps them to either recover from or withstand parasites.