Learn about a tongue–eating parasite that infests the mouths of some fish that we eat, in this episode of Gross Science from NOVA. Juveniles enter fish through their gills. A female attaches itself to the base of the tongue, sucking blood until the tongue dies. The parasite continues to suck blood or mucus from the fish, while the fish may start using the parasite as a prosthetic tongue. This resource is part of the NOVA: Gross Science Collection.