The pilot fish is carnivorous and follows sharks and ships apparently to feed on parasites and leftover scraps of food. It was formerly thought to lead, or “pilot,” larger fishes to food sources, hence its common name.
Yarrell, William (1841). A History of British Fishes (2nd. ed.). John van Voorst. p. 170. The pilot-fish has been so often seen, and occasionally taken on our southern coast, as to be entitled to a place among British Fishes[.]
Froese, Rainer and Pauly, Daniel, eds. (2019). "Naucrates ductor" in FishBase. August 2019 version.