Hello! Wonder if someone could help me… I’ve noticed my yellow koi has developed red spots over his face. Another 1 or 2 of my goldfish also have red marks on them. I’ve attached a photo to show what it looks like.

What could it be and does it require some form of treatment? I have treated the pond 48hrs ago using Cloverleaf Answer for the blanketweed but I’m not sure if the red marks were there before or have developed since or are completely unrelated?

Thanks in advance for any help!