Leeches, Lice and Lampreys: A Natural History of Skin and Gill Parasites of ... - Graham C. Kearn - Google Books

https://books.google.de/books?id=Sdpru9qKtOUC&pg=PA31#v=onepage

Many different kinds of animals have adopted a parasitic life style on the skin and gills of marine and freshwater fishes, including protozoans, flatworms, leeches, a range of crustaceans and even some vertebrates (lampreys). There is a parasitic barnacle,…