Large Mouth Bass

Category: Wildlife

Also known as the widemouth bass, bigmouth bass, and the black bass, the largemouth bass is one of the most commonly hunted freshwater fish in the world. Originally endemic to the United States, it is now widely distributed around the planet.

Large Mouth Bass

Large Mouth Bass

Scientific & Common Names

Kingdom - Animalia

Phylum - Chordata

Class - Aptinopterygii

Order - Perciformes

Family - Centrarchidae

Genus – Micropterus

Species – M. samoides

Common Names – Largemouth Bass, Bigmouth Bass, Widemouth Bass, Potter's Fish, Bucketmouth, Black Bass


Largemouth bass are members of the sunfish family (Centrarchidae). They can be distinguished from their closest relatives - smallmouth or spotted bass - by the size of their mouth, which extends beyond the eye. Their spiny dorsal fins to the front are also separated from the softer dorsal fins to the rear, while they are fused in other bass. Their coloration tends toward an olive or dark green, fading to greenish yellow on their sides and a creamy off-white on their belly. A dark, uneven, stripe follows the lateral line along their sides. Their average lifespan in the wild (11-15 years) is twice as long as in captivity (6 years). As the world record of 22 pounds 4 ounces shows, they can reach sizes of over two feet and 20 pounds, but those sizes are rare. The average size for a largemouth bass is varies greatly from 10-20 inches and 1-2 pounds, although 5-13 pounds individuals are not uncommon. They will sometimes interbreed with other close relatives, such as the smallmouth bass.


Male largemouth bass use their tales to sweep out a nest in 2-8 feet of water. They will then nudge or encourage a female into the nest where she will lay between 2-43 thousand eggs before exiting the nest. The male then broods the eggs, sometimes from multiple females, for 5-10 days before several thousand fry hatch. The tiny fry, transparent and only about 3 millimeters long, remain in the relative safety of the nest, with their father standing guard against predators, for another week before setting off on their own. During this first week, they survive on the nutrients from their yolk sack. Upon leaving the nest, the young, which would then be a light green, school together and feed on zooplankton. They become mature at about four months old.


A warm water fish, largemouth bass tend to stay in shallower water and do not stray in to the deeper, coolers areas of their habitat unless the surface temperatures become intolerably cold. Predatory even as fry, they first feed on zooplankton before moving on to small fish and insects as juveniles and finally, as adults, they feed on larger fish, crayfish, turtles, amphibians, and even birds. They will feed at any time of day, but the morning or evening twilight are their peak feeding times. While juveniles may become prey for any number of fish, birds, or reptiles, adults are considered top tier predators and have little to fear.


The oldest fossil of a bass was found in Texas and dated to 23 million years ago. The eleven current species of black bass were believed to have diverged from others eleven million years ago. The genus micropterus was believed to have emerged about 26 million years ago, during either the Oligocene or Miocene epochs.

Present Status

Largemouth bass are in no danger of extinction. They are, however, a danger to other animals. Since they are so widely introduced, they have had a negative impact on many of their new homes. The Atitlán Grebe of Guatemala, a subspecies of the pie-billed grebe, is believed to be extinct and part of the blame for the loss of the bird is placed on the introduction on largemouth bass. In Europe - especially Spain - the introduction of European pike and North American largemouth bass are considered to be among the biggest threat to native species, behind only the mass extraction of water for human usage.


  1. Invasive Species: What Everyone Needs to Know by Daniel Simberloff
  2. Speciation in North American Black Basses, Micropterus (Actinopterygii: Centrarchidae) Thomas J. Near, Todd W. Kassler, Jeffrey B. Koppelman, Casey B. Dillman, and David P. Philipp
  3. Ecology of North American Freshwater Fishes by Stephen T. Ross
  4. Peterson Field Guide to Freshwater Fishes, Second Edition (Peterson Field Guides) by Lawrence M. Page, Brooks M. Burr
  5. Invasive Species in a Globalized World: Ecological, Social, and Legal Perspectives on Policy by Reuben P. Keller and Marc W. Cadotte