Hi all, we have a choc ghost knife at work who has some quite wierd creatures on him at present. They have been there a while and are increasing slowly. They are approx 5mm long, 1mm wide and white (not see thru), like a super elongated oval- very much a leech shape. Some of them look to have a 'head' buried in its body yet others dont. They dont wipe off, you have to scratch with your fingernail and they do feel quite hard, the whole thing seems to be holding on quite securely, they arent dangling off. They are easy to squash and just turn into mush without any hard casing or anything. They dont seem to be bothering him nor do any of the other fish have them.
I have googled fish flukes and leeches and they dont seem to look much like these do.
Would a course of acriflavine or copper be the way to go?