[AlanK]

Hi Boo, I don't know if your problem is resolved as yet. Two of my koi have exactly the same problem. I tried to sort it last year by asking on Koi keepers. When I didn't get any joy, I just left it alone. The spot is still there a year on but is the same colour as the rest of the surrounding area. It does not seem to bother either koi and does not look inflamed or sore.

[Gazfish]

Hi Guys,

I am not 100% but could this not be Dermocystidium which can be a pain to treat and there is no off the shelf medication for it and people have tried all sorts and you normally need to be aggressive with it.