I know, without a photo it is a guess. I have tried like hell to d my homework, googled through five pages of photos, almost 10 on the web. Nada. Not exactly my area of expertise as I really have not had issues in that area. I've seen a bunch of the koi problems, but parasites are not high on the list. And most of the LMB parasites are internal. I am thinking I need a good web page showing them with photos, or a fish dept. Maybe F and G or some ag university. Local would be better. I care enough to look for the answer. Problems could be ahead, or I could figure out where they came from. Ironically this pond has always had the cleanest, healthiest fish. Not any more.