California grunion
Small silvery fish that spawns on sandy beaches during high tides.
The California grunion is a slender ray-finned fish native to the Pacific coast of North America. It is known for its unique behaviour of beaching itself on sandy shores to lay eggs during specific tidal cycles.
- Grows to a maximum length of 19 cm
- Spawns on sandy beaches during high tides
- Eggs hatch only after sand agitation by waves
- Found from Monterey Bay to Baja California
- Feeds on plankton such as copepods
What it is
This species is a small, elongated fish with a deeply forked tail. Its body is greenish on the upper side and silver underneath, featuring a blue cheek patch and a lateral stripe. The dorsal fin has two sections with spines and soft rays, while the anal fin sits directly below the first dorsal section. Adults reach a maximum length of 19 cm.
Where it lives
The fish lives in the eastern Pacific Ocean, ranging from Monterey Bay in California down to Baja California. It is also present in the Gulf of California. Populations are rare north of Point Conception. These fish inhabit shallow waters, staying between the surface and depths of about 18 metres.
How it lives
They feed on tiny planktonic organisms like copepods. Larger predators such as California halibut, rock bass, and white croakers hunt them. Shore birds including whimbrels and marbled godwits probe the sand for their buried eggs. Other threats to the eggs include sandworms, ground squirrels, isopods, beetles, and flies.
Breeding and life cycle
Spawning occurs from March to August on nights following the full moon peak tide. Females bury themselves tail-first in wet sand to deposit eggs, while males release milt around them. The process takes about thirty seconds. Eggs remain buried until spring tides associated with the new moon agitate the sand, triggering hatching after roughly ten days of development.
Fish and people
Local fisheries target this species during mass spawning runs when they beach themselves. People catch them for food or use them as bait. This behaviour of jumping onto land to spawn is shared only with capelin and grass puffer among fish species.
Questions people ask about California grunion
Where does the California grunion live?
It is native to the eastern Pacific Ocean, found from Monterey Bay in California south to Baja California and in the Gulf of California. It inhabits coastal waters from the surface down to 18 metres deep.
How does the California grunion reproduce?
Females bury themselves in wet sand on beaches during high tides after the full moon to lay eggs. Males release milt around them. The eggs hatch about ten days later when new moon tides agitate the sand.
What do California grunions eat?
They feed on plankton, specifically small organisms such as copepods. They are part of the marine food web, serving as prey for larger fish and birds.
Good reading and sources
- Leuresthes tenuis on WikipediaEncyclopedia
- More photos on Wikimedia CommonsPhotos
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Leuresthes tenuis", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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