Koi diseases
Koi diseases are common, especially when the water composition or water quality is not good. When koi are infected, it is important to look closely at the symptoms and determine what condition the fish have.
A sick koi can be recognized by lethargic behavior or spots on the skin; other symptoms include scouring the bottom or other abnormal behavior.
The most common koi diseases are:
| Abdominal dropsy | Chilodonella | Costia |
| Cryptobia | Threadworm | Hole Disease |
| Skinworm | Carp aphid | Gill worm |
| Koi herpes (KHV) | Koi pox | Oodinium |
| Protozoa | Saprolegnia | Trichodina |
| Fin Rot | Fish TB | White spot |
Koi disease prevention
When a koi is sick, there are different types of medications available. It is wise to quarantine the sick koi outside the pond or even better to prevent koi diseases:
- Strong fluctuations in water quality can sometimes cause the resistance of the koi to decrease, leading to koi diseases. Also regularly check and measure the water quality of the pond water. This can easily be done with a water test kit
- To maintain water quality, a good filter is a godsend. Thus, polluted particles in the water are absorbed. If a pond filter also contains activated carbon, pathogens can be filtered out of the water.
- To prevent a sick fish in the spring, it is important to feed the fish during the summer months with a good quality food in which all the important nutrients, vitamins and minerals are present in ample amounts. In this way, the resistance of the koi during the winter months is maintained.
- Don’t put too many koi in the pond. The standard is a maximum of 1 koi per 1,000 gallons of water.
