My goldfish have large warts

[Jason F]

Hi, I'm sure there are many posts on this topic, but if somEone could please post some advice. I have a shallow outdoor pond with Koi and goldfish in it. Two of the goldfish have large warts on them (no fluffy bits). They have had them for a few years now and seem fine otherwise. Should I do saltwater treatments? I did a couple of strong potassium permanginate treatments (and then neutralised) to the entire pond and filtration systems to kill everything except the fish, a year ago, but it made no difference to the warts on the fish.