Naucrates ductor

From "The Fisheries and Fisheries Industries of the United States", by George Brown Goode (1887).

http://www.photolib.noaa.gov/historic/nmfs/figb0368.htm

Source: https://commons.wikimedia.org/wiki/File:Naucrates_ductor.jpg

The pilot fish (Naucrates ductor) is a carnivorous fish of the trevally, or jackfish family, Carangidae. It is widely distributed and lives in warm or tropical open seas. The pilot fish congregates around sharks, rays, and sea turtles, where it eats ectoparasites on, and leftovers around the host species; younger pilot fish are usually associated with jellyfish and drifting seaweeds.