Grunion are known for their unusual mating ritual wherein at very high tides, the females come up on to sandy beaches where they dig their tails into the sand to 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.

Silversides differ from true smelts of the family Osmeridae in that they lack the trout-like adipose fin.

Young grunion grow rapidly and are about five inches long by the time they reach one year old and are ready to spawn.

California grunion spawn on beaches from two to six nights after the full and new moon beginning soon after high tide and continuing for several hours.

Counts of maturing ova to be laid at one spawning ranged from about 1,600 to about 3,600, with the larger females producing more eggs.

[4] Although some other fish species leave their eggs in locations that dry out (a few, such as plainfin midshipman, may even remain on land with the eggs during low tide) or on plants above the water (splash tetras), jumping onto land en masse to spawn is unique to the grunion, capelin and grass puffer.

The reduction of spawning habitat due to beach erosion, harbor construction, and pollution is believed to be the most critical problem facing the grunion species.

[citation needed] An isopod, two species of flies, sandworms, and a beetle have been found preying on the eggs.

While the population size is not known, all 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.

A fishing license is required for persons 16 years and older to catch grunion, and they may be taken by sport fishermen using their hands only.

Archeologists have found fossil grunion otoliths (tiny, bonelike particles or stony platelike structures in the internal ear of lower vertebrates) at various Native American campsites.

Grunion were mentioned by Spanish explorer Juan Rodríguez Cabrillo in his ship's log dated around 1542.