grunion

Grunions are small, slender fish belonging to the family Atherinidae, found along the Pacific coast of Mexico and the United States. They are most famous for their unique spawning behavior, which occurs on sandy beaches during high tides, typically after the full or new moon. These spawning events are known as "grunion runs."

During a grunion run, females will wriggle tail-first into the wet sand to lay their eggs, while males will curl around the females, fertilizing the eggs. The fish then ride the receding waves back to the ocean. The eggs remain buried in the sand, incubating until the next series of high tides, usually two weeks later. This timing allows the hatching eggs to be washed out to sea. This specific method of reproduction is a key characteristic of grunion.

The most well-known species is the California grunion, Leuresthes tenuis. Their diet consists mainly of plankton and small crustaceans. Grunion are also a popular target for recreational fishing in Southern California, where regulations are in place to manage the fishery. Conservation efforts are important due to the specialized habitat requirements for their spawning.