Grunion lay their eggs. The male then wraps himself around the female to deposit his sperm, and for the next 10 days the grunion eggs remain hidden in the sand. At the next set of high tides, the eggs hatch and the young grunion are washed out to sea. A related species, the false grunion ("Colpichthys regis") lives in the Gulf of California. Although the fish looks and acts similarly, it does not have the same breeding method. The currently recognized species in this genus are: Grunion were originally classified as part of the Atherinidae family of silversides, but are now
Grunion research points to a restricted resource that is adequately maintained at current harvest rates under existing regulations. In the 1920s, recreational fishing of grunion caused definite signs of depletion resulting in a regulation passed in 1927 that established a closed season of three months from April until June. Grunion stocks improved and in 1947 the closed season was shortened to the months of April and May. This closure is still in effect to protect grunion during their peak spawning period. The periodic appearance of the grunion on Southern California beaches, and the act of catching them, is locally known as