Grunion are two fish species of the genus Leuresthes: the California grunion, L. tenuis, and the Gulf grunion L. sardinas. They are sardine-sized teleost fishes of the Atherinopsidae family of New World silversides, found only off the coast of California, USA, and Baja California, Mexico, where the species are found on both the Pacific Ocean and Gulf of California coasts.