The Koi Health Checklist

Published on October 16, 2018

koi diseases
Catching and investigating koi diseases early can make all the difference in saving your finned friends.

Owning Japanese koi can be a rich, lovely and rewarding experience. These “living jewels” can live up to 60 years, bringing you a lifetime of good luck and abundance.

In return, you must learn to understand the language of koi so you can keep them healthy and happy. My name is Taro Kodama and at Kodama Koi Farm (, we import high-end Japanese koi for sale  and have created an in-depth koi symptoms and diagnosis checklist for you to keep handy and refer to often.

I hope that this article will teach you how to check for koi health, and that you will use this same checklist that we refer to at the farm for quickly reviewing the health of our koi.

Using the Koi Health Checklist

After you have downloaded the checklist, start by reading the introduction on how to observe koi. You will find that the checklist groups categories for review of koi health with descriptions of potential symptoms along with possible causes. It is meant to be a quick review of the different areas of observation to help you get a better understanding. Refer to the full article “Help is My Koi Sick?,” to see the Koi Diseases by Symptoms Table and the Treatment and Control of FIsh Disease Table.

How to Understand Koi Behavior

The first step is becoming familiar with your koi’s normal behavior. This will make any abnormal behavior jump out at you and give you the best chance of catching an illness early.

pond owners observing koi fish
Start by observing how your Koi swim from a distance and then observe them from close while feeding to check if every Koi comes up to eat like usual.

Watch how koi group together when they swim. If you notice any koi swimming separately or lethargically, this might indicate a bacterial infection.

Are any koi swimming erratically or rubbing their abdomens along the wall or bottom? Parasites can affect mental behavior, and koi may be trying to rub them off.

Appetite is affected by sickness, although even lethargic koi may move quickly when they see you coming to feed. Watch to see if any new or suspected koi are not really eating. They may come for a few nibbles, but if they are sick, they won’t feed as heartily as the healthy koi.

Always look for extra food that is left over. Not only does this indicate that your koi are not eating their normal amount, but the extra food that is left to rot will also throw off the nitrogen balance in the water and exacerbate any current illnesses. Keep feeding to about as much as they can eat in a minute’s time, twice a day.

How to Diagnose and Treat Illnesses

Once you suspect an illness, taking the time to try and diagnose it more specifically will save you time and money. If you go to a fish store and tell them your koi are sick, many people will sell you expensive medicine without knowing what it is you are even trying to treat. Taking blind stabs is not only wasteful of your money and time, but you also risk the koi dying before you treat them properly.

quarantine koi tank ponds
Use a smaller tank for removing any koi in question to keep others from getting sick and to analyze them further.

After an imbalance or sickness occurs, the health of your koi can decline very quickly. It is important that you know whether you are treating parasites,or a bacterial infection, or if you need to address water, oxygen or nitrogen issues. Use the table in “Help is My Koi Sick?” to diagnose, and with a little investigation, you will be able to know how to treat your koi properly.

Some treatments will be necessary to administer to the the entire pond, and if you suspect most of your koi are sick, this is the best way to be safe. Other times, you may be able to remove the individual koi and treat them in a smaller koi quarantine tank. This is why catching signs of disease early can be so beneficial. You can mitigate the pain caused to fish, purchase less medicine and, most importantly, reduce the issues with the rest of your pond.

We hope you take this advice to heart and do your due diligence to better understand the language of koi for improving their health. Keeping an eye on your koi friends and acting quickly can save both you and the koi the suffering caused by sickness and casualties.

Your koi will bring you a lifetime of enjoyment and good fortune. You must only do your part in return.

1. It is recommended that injections be performed under a vet’s guidance and/or supervision.

2. Kodama Koi Farm & Kodama Koi Garden are not responsible for loss of fish, damage to pond equipment or other liabilities or damages incurred directly or indirectly from the use of the information contained in this guide (the “Koi Health Diagnostics Chart/Manual”).

3. Customer is responsible for performing any treatments or administering any medications indicated in this guide. Recommendations and instructions are made based on generally accepted circumstances & methods and may not apply to special or exclusive circumstances. Customer is ultimately responsible for observing & determining the situation and choosing the most applicable course of action.

4. Read all information, instructions and warnings carefully before using and administering any medications, especially injections. Those using this guide must also read all instructions and warnings provided by the manufacturer or printed on the particular product label prior to using the product. Customer is responsible for taking any precautions and understanding all warnings provided by different medications and products mentioned in this guide or otherwise.

Japanese Koi Kodama

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