Koi Diseases – How to Examine Your Koi

What happens when your Koi fish get sick? There aren’t a lot Koi fish Vets around. That’s why it’s important for Koi owners to at least know some of the basics of Koi diseases and how to deal with them. At a minimum every Koi owner should know how to examine their fish as a first step in diagnosing Koi diseases that will surely arise at some point.

The first thing you have to be able to do is catch or net your fish. This may not be as easy as it sounds. It can be made more difficult by the Koi’s temperament and state of health. The best advice is to practice netting your fish when they are healthy so you’ll know what to do when they get sick.

A Koi’s ailments can range from the very obvious to quite subtle. The only way to find out for sure what the problem might be is to give them a good comprehensive examination. While the netting and bowling will increase the stress on your fish, you need to be able to examine them thoroughly.

When you have the fish in the bowl, look for external parasites.  Parasites are one of the most common Koi diseases. They are almost always present and are easily passed from fish to fish. The problem becomes more acute when the weather warms up. It’s then that the parasites become active.

Look for any open wounds on the fish or any unusual appearance to the body or fins. Make sure you lift the fish out of the water and look for any lesions or open wounds on the underside. If you don’t find anything unusual, for him back in the bowl and drain most of the water out. This is so you can take the next step in the examination – taking a swab or scaling.

Taking a swab or scaling isn’t as hard as it sounds.  You want to know how to do this because at some point a Vet may want you to send the results to a lab for further testing. Take a wet cotton swab and drag it in the direction of the scales (never against) around the gill covers, the base of the dorsal fin and along the base of the tail. This will gather some of the mucous that’s found on the fish.

If the swab in inconclusive a slightly more invasive process – a skin scrape may be needed. This is basically the same procedure as a swab but you use a firmer object such as a glass slide used with a microscope to scrape the skin. You want to gently but firmly scrape the skin to gather some of the mucous. When you taken the scraping ad a drop of water and cover the slide. Most of the time, your vet can get you the proper materials for taking the scraping or swab. A good pet store can also help or the check with the dealer or breeder where you purchased your fish.

Learning how to examine your fish is an important step in diagnosing and treating Koi diseases.