Isopods or?

[Aquattro]

Probably the same isopods that are in my tank. Use a tall narrow vase or glass pop bottle with some bait at night, you can catch a few every night. FWIW, the only time I saw them on the fish, they were right at the edges of the fins, not biting into the fish body at all. And I haven't seen any for a month now, so hopefully I got them all.