noun, plural (especially collectively) rud·der·fish, (especially referring to two or more kinds or species) rud·der·fish·es.

any of various fishes having the habit of following behind ships, as a pilot fish.

Origin of rudderfish

First recorded in 1725–35; rudder + fish Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019