Sick Koi Please help him...

[GBBUDD]

I'm no expert and this is just a guess but it looks bacterial here is a web site from a very known and respected breeder

How to Make Medicated Koi Food for Bacterial Infections

Learn how to make your own medicated koi food at home now and use our special package of everything you need to make your own food. We will go through bacterial infections and what to use for parasites as well.

www.kodamakoifarm.com

 

[WaterGardener]

As someone else has suggested, go to Koiphen.com and ask them. They are very knowledgeable about diseases and are very willing to help.

My guess, and it's just a guess, would be excessive slime coat from poor water quality. Test your water and make sure that's not the problem. Most issues with sick fish come from bad water and with good water, most will recover on their own.

Your fish looks very thin to me as well.

 

[Mmathis]

@RichB How is your fish? Did you ever find out what was wrong with it? What did the folks on KOIPHEN.COM have to say?