Ergasilidae

Ergasilidae is a widespread family of copepods and comprises many species. The type genus is Ergasilus. With a few doubtful exceptions all ergasilids are parasitic on fishes.

==Biology== Various species of Ergasilidae parasitise hosts in various habitats, mostly freshwater, but some attack marine species, especially euryhaline fishes such as mullet. Because the best-known species are adapted to attack the gill filaments of the fishes, Ergasilidae are known by common names such as gill lice. However, some species have been found infesting, and presumably causing, external skin lesions of fish.