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pilotfish

[pahy-luh t-fish]
noun, plural (especially collectively) pi·lot·fish, (especially referring to two or more kinds or species) pi·lot·fish·es.
  1. a small, marine fish, Naucrates ductor, often swimming with sharks.
  2. any of various other fishes having similar habits.

Origin of pilotfish

First recorded in 1625–35; pilot + fish
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for pilot fish

pilot fish

noun
  1. a small carangid fish, Naucrates ductor, of tropical and subtropical seas, marked with dark vertical bands: often accompanies sharks and other large fishes
  2. any of various similar or related fishes
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012