My koi has developed red patches - ??

[southkoistar]

I am looking for some advice on what may be wrong with my Koi and what treatment to give them. Goldy is nearly 11 and has never had any issues before but in the last week I have noticed some marks appearing mainly around the face area which look red and are prominent because of her gold colouring. Goldy lives with one other koi who is over 25 years old and they don't appear to have the same issue although they are a completely different colouring. Any help from the forum and what treatment to try. I don't want to guess what may be wrong and give the wrong treatment.

[Alburglar]

Probably not bacterial, could be Secondary infection / irritation due to parasites?
You need to scrape it... Or find someone locally who can help you do that...