Not all gyrodactylids are species specific.
As for potassium permanganate, I disagree with Untergasser. I've used it on
millions of various tropical fishes without significant harm. I like it
because it is effective against bacteria and external protozoans, and it
isn't carcinogenic like most of the other chemicals used on fishes. That
said, like all chemicals, if not used properly KMnO4 can be harmful.
Denise