Connect with us

Report an Invasive Species

Largemouth Bass

Largemouth Bass

Largemouth Bass

(Micropterus salmoides)

Tags: Aquatic

Identification and Reproduction


  • The largemouth bass is a carnivorous freshwater fish. 
  • This fish is olive-green to green-grey, marked with a series of dark and even black blotches that form a horizontal stripe across the body. 
  • As noted by its name, this fish is the largest out of all the black basses, it can reach a length of 40 cm. 

  • Two dorsal fins are fused together. 
  • Has a long, wide lower jaw that is slightly longer than the upper jaw. 


  • Populations increase rapidly, as females lay up to 45,000 of eggs at a time and can spawn multiple times in a season. The number of eggs laid is impacted by her size. 
  • Spawning occurs in late winter between January and February in the southern parts of US but will occur between May and June in northern regions. 
  • These fish can reach sexual maturity as early as 3 months. 

Habitat & Ecology

  • The largemouth bass lives in all water types, swamps, ponds, lakes, reservoirs, creeks and even large rivers. 
  • Young largemouth bass primarily feed on small bait fish, scuds, small shrimp and insects. 
  • Adult largemouth bass will feed on smaller fish, shad, snails, crawfish, amphibians, bats and even small water birds. 
  • Prefers warm, shallow waters and are often found near stumps and aquatic vegetation, especially waterlillies, cattails, and other pondweeds. 
  • These fish will grow much more slowly in weedy and vegetated waters, as this makes catching prey more difficult. 


  • In waters with little to no vegetation cover, largemouth bass can devastate the prey population. 
  • As an introduced species it can permanately alter the native food web by eliminating native species. 
  • Have been known to cause local extinction of native fish and amphibian species. 
  • This fish is also capable of carrying hundreds of parasites that can spread to native species. 


  • Report this species if you think you have seen it; take photos, note exact location, date and any identifying features. 
  • Always clean, drain and dry your boat and water equipment before leaving a waterbody. 


Download BC's Invasive Species Alert for Largemouth Bass here

For more information please refer to the Animal Diversity Web datapage on Micropterus salmoides: American black bass here

For more details check out the Invasive Species Compendium datasheet on Micropterus salmoides (largemouth bass). 

Header photo (Yinan Chen).