Koi Health

Everyone hates dealing with a sick koi but just like people, koi occasionally get sick. The best formula for koi health is PREVENTION. Most preventative measures revolve around water quality and observing your koi closely

Mark Bodycott of AquaMeds (and USAKoi)  identifies the five most common causes of sick koi.

  1. Poor Water Quality: 70% of all koi sickness is caused from poor pond water quality.
    1. Insufficient filtration
    2. Insufficient aeration
    3. Not completing partial water changes on a weekly basis
    4. Not testing water parameters regularly
    5. Cleaning filtration equipment and media that kills “good” bacteria.
  2. Insufficient Quarantine: New koi should always be quarantined to reduce the chance of introducing pathogens into your pond environment.
  3. Feeding problems: overfeeding, underfeeding, feeding a poor diet
  4. Overcrowding: stocking your pond with more koi than your filtration system and water capacity can handle
  5. Chemical Soup: applying a variety of koi medications without properly identifying the illness and correcting water quality.

Where can you find information about identifying and treating koi illnesses?

  1. Books: 
  2. Websites:
  3. Your koi dealer, Charlotte Koi Club members, other koi keeping friends, members of koi hobby groups on Facebook.

The bottom line is select one source or knowledgeable person to work through your koi health problem. Many koi keepers will ask several individuals how to treat a koi problem and will receive conflicting information. Some hobbyists will implement a variety of solutions that counteract each other and cause greater damage to the koi.

Basic items you should have in your koi health cabinet. The following list is not all inclusive but having a few standard medications, water test kit and microscope will allow you to properly tend to many koi illnesses. Your water test kit should be used at least weekly to stay on top of your water parameters.

  1. Water test kit, additional tests for GH and KH may need to be purchased separately. 

  2. Broad Spectrum Disease Treatment such as:

  3. Praziquantel such as:

  4. Salt:

  5. Iodine such as:

  6. Microscope, typical compound microscope such as:



  • Maintain water quality with regular water changes.
  • Test your water parameters weekly.
  • Observe koi regularly and address problems as soon as possible