Lernaea nodosa; Print; Lernaea (also incorrectly spelled Lernea) is a genus of copepod crustaceans commonly called anchor worms; parasitic on freshwater fishes. They mate during the last free-swimming (copepodid) stage of development. After mating; the female burrows into the flesh of a fish and transforms into an unsegmented; wormlike form; usually with a portion hanging from the fish's body.