These fish are famous for their spawning behavior, which is so remarkable that it evokes an “I don’t believe it!” response from people who hear it described for the first time. Grunion leave the water at night to spawn on beaches during the spring and summer months. For four consecutive nights, beginning on the nights of the full and new moons, spawning occurs after high tides and continues for several hours. As waves break on the beach, grunion swim as far up the slope as possible.Spawning occurs from March through August, and occasionally in February and September. Peak spawning is late March to early June.