Pilot fish

The pilot fish (Naucrates ductor), a member of the Carangidae family, commonly known as the trevally or jackfish family, is a carnivorous species inhabiting the warm or tropical open seas worldwide. This species is known for its unique symbiotic relationship with marine hosts such as sharks, rays, and sea turtles, feeding on ectoparasites and consuming food remnants. Juvenile pilot fish often associate with jellyfish and floating seaweeds. Additionally, pilot fish have been observed accompanying ships over long distances; some have even been found as far afield as County Cork, Ireland, and along the shores of England. Historically, this behavior led to the belief that pilot fish guided ships along their courses.

Pilot fish exhibit a coloration that ranges from dark blue to blackish-silver, with a lighter hue on the belly. When excited, they may display a temporary color change, where the dark bars vanish, and the body becomes silvery-white with three prominent blue patches on the back. A distinguishing feature of the pilot fish is its five to seven dark transverse bands. The species can reach a length of 60–70 cm.

While the pilot fish is considered edible with a reportedly pleasant taste, it is seldom available due to its unpredictable behavior upon capture. It predominantly associates with the oceanic whitetip shark (Carcharhinus longimanus), forming a mutualistic relationship—gaining protection while providing parasite removal services to the shark. Historical accounts from sailors suggest a significant bond between pilot fish and sharks, with anecdotes of pilot fish following ships for extended durations after "their" shark was captured and displaying signs of distress at its absence. It is uncommon for sharks to prey on pilot fish, and smaller individuals have been frequently observed cleaning sharks’ mouths.

The term "pilot fish" has multiple purported origins. One explanation is that seafarers believed these fish, appearing near ship bows close to land, guided them back to port. Alternatively, it was incorrectly assumed that pilot fish led sharks to food or, as legends suggest, navigated ships, whales, and swimmers to safety. The pilot fish also serves as a metaphor for entities that lead or accompany a larger threat, often analogous to scavengers or looters.

In Greek mythology, the pilot fish appears in the story of Pompilus, a sailor transformed into a pilot fish by Apollo as punishment for aiding the nymph Ocyrhoe. Additionally, Pancrates of Arcadia revered the pilot fish as a sacred creature dedicated to Poseidon, forbidden for consumption—a cautionary tale recounted through the story of Epopeus, a fisherman who faced dire consequences for eating the fish.