Largemouth Bass

Identification & Biology
Alias' : Black Bass, Brown Bass, Green Bass, Widemouth Bass, Bigmouth, Bucketmouth, Black Trout
Latin Name : Micropterus  salmoides 
Category : Fish
Description :
  • Bright green to olive on the dorsal (back side), lighter green to golden on body sides, and white on ventral (under) side 
  • Two dorsal (back) fins that are fused together; anterior section of fin has spines and posterior section has soft rays 
  • Mouth that extends past the center of the eye 
  • Horizontal, dark spotted line running from gills to tail 
  • Grows to 30-40 cm long 


The Largemouth Bass is a carnivorous freshwater game fish, and the largest species of the black basses. The fish lives 16 years on average and have been known to live up to 20 years.  Adult Largemouth Bass can feed on almost anything- perch, sunfish, minnows, crayfish, insects, frogs, and even small aquatic birds. Adults are solitary fish, although occasionally several bass will congregate in areas with abundant food supplies. A bass under 5 cm, known as a “fry”, does not act as a predator, but instead will feed on zooplankton and insect larvae. Largemouth Bass are often sought after by anglers because of the excitement of their “fight”, meaning that the fish vigorously resist being hauled into the boat or onshore after being hooked.  

Largemouth Bass can be confused with the non-native Smallmouth Bass (Micropterus dolomieu). In comparison to Largemouth Bass, Smallmouth Bass have vertical dark bands on sides, and have a smaller mouth that only extends to the beginning of the eye.  

Look Alikes

Largemouth Bass are a native fish species to eastern and central North America, however, they not native to B.C. They have been introduced into a few lakes in the Lower Mainland, Vancouver Island, Okanagan, and Kootenay regions. They are usually the apex predator in their habitat. They will hide between rocks, among water vegetation, or under roots and limbs of sunken trees, striking at their prey from the shadows. Bass prefer quiet, calm, and warm water but are very adaptable to other conditions. They are found in rivers, lakes, ponds, reservoirs, and streams. Lack of dietary restrictions allow them to invade a variety of habitat types.  

Impact & Risks
  • With little or no cover, bass can devastate the prey population. 
  • Under overhead cover, such as overhanging banks, brush, or submerged structure, such as weed beds, points, humps, ridges and drop-offs, the largemouth bass uses its senses of hearing, sight, vibration, and smell to attack and seize its prey.  
  • These fish are often a danger to native fish fry such as Salmon and Trout, posing a risk to recreational and commercial fisheries. 
  • Juvenile Largemouth Bass are able to demonstrate trophic plasticity, meaning that they can adjust their feeding habits to obtain the necessary amount of energy needed to survive. The ability to do such, allows them to be successful as invasive species in relatively stable aquatic food webs.  
  • They are capable of carrying parasites that can harm native fish species. 
Prevention & Mitigation
  • Do not possess, breed, ship or release Largemouth Bass in B.C. Movement of live fish is prohibited in B.C.
  • Use of live bait is prohibited in B.C. 
  • Do not release aquarium fish into the wild. 
  • Properly clean,  drain,  dry  your boat and equipment before entering a new water body. 
  • CLEAN  off all plant parts, animals, and mud from boat and equipment (e.g. boots, waders, fishing gear). Use a power wash station if available 
  • DRAIN  onto land all items that can hold water (e.g. buckets, livewells, bilge, and ballast) 
  • DRY  all items completely before launching into another body of water 
  • Raise awareness to avoid the spread of this species in B.C. 
  • Report Largemouth Bass, or any other invasive species via the Report Invasives phone app, that is available from the provincial website.
Treatment & Disposal


Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.