California Aquatic Invasive Species (AIS)
University of California
California Aquatic Invasive Species (AIS)

Invasive Fish Species

Mississippi Silverside

Scientific Name

Menidia beryllina (M. audens) - Visit ITIS for full scientific classification. 


  • Small, freshwater fish.
  • Slender body shape reaching about 4 inches long.
  • Pale, semi-translucent skin, with a distinct yellowish-green color.
  • Can be confused with Topsmelt in estuarine environments. 
  • Most common in shallow, warm water lakes, reservoirs, and estuaries.
  • They school in large numbers near the surface of the water, concentrated in protected areas with gravel or sandy bottoms.
  • Can tolerate high salinity levels (up to 3 ppt). 
Invasion Pathways and Distribution
  • Mississippi River and East Coast native.
  • In 1967 Mississippi Silversides were introduced into Clear Lake, California to control a nuisance insect species.
  • Now found throughout Northern California, and have spread to Southern California via the California Aqueduct. 
  • Visit USGS for a current U.S. distribution map. 
Life History
  • Mating occurs anytime April- September when the water is warm.
  • Females lay eggs in vegetation beds.
  • The eggs attach to surfaces, and hatch up to one month later.
  • The young fish develops for several weeks until it joins a larger school. 
  • It has been reported that Mississippi Silversides have outcompeted certain native fishes for food in Clear Lake California.
  • They are also known to feed on the eggs and larval forms of other fishes.
  • This increase in competition and predation could potentially decrease the number of native fishes, and lower overall species diversity.
References and Useful Links

For references by category and links to other useful AIS sites see our LEARN MORE page.

Top of page

Webmaster Email: