- (idiomatic) To be dead as a result of being murdered; usually also means the corpse has been dumped in a body of water.
- Probably first used in the motion picture The Godfather (1972): "Luca Brasi sleeps with the fishes."
A similar reference can be found in Herman Melville's Moby Dick, wherein the second mate Stubb soliloquizes: "when Aquarius, or the Water-bearer, pours out his whole deluge and drowns us; and to wind up with Pisces, or the Fishes, we sleep. (Melville, Moby Dick, ch. 94).
Earliest known reference for this phrase can be found in the epic Greek poem, The Iliad, by Homer. During Book 21, Achilles slays Lykaon, a son of Priam, and throws him in a river. Achilles taunts him as he dies, saying "Lie there now among the fish..." (Lattimore translation) or, "Make your bed with the fishes now..." (Fagles translation). In other words, sleep with the fishes.