Largemouth Bass (Micropterus salmoides)

The largemouth bass is the biggest and most renowned member of the Centrarchidae family of sunfish and its subgroup known as black bass. It is sometimes confused with the smallmouth in places where both species occur, and also with the spotted bass (see: Bass, Spotted). One subspecies, the Florida largemouth bass (see: Bass, Florida Largemouth), M. salmoides floridanus, is capable of attaining large sizes in appropriate waters but is otherwise similar.


The largemouth bass has an elongated and robust shape compared to other members of the sunfish family. It has a distinctively large mouth, as the end of its maxillary (jaw) falls below or beyond the rear margin of the eye; the dorsal fin has a deep notch separating the spiny and soft rays; and the tail is broad and slightly forked.

Although coloration varies greatly and is especially dependent on biological factors and host environments, the largemouth bass generally has a light green to light brown hue on the back and upper sides, white lower sides and belly, and a broad stripe of diamond-shaped blotches along the midline of the body.

This stripe particularly distinguishes it from its close relative the smallmouth bass, as does the upper jaw, which in the smallmouth does not extend past the eye. The largemouth lacks a tooth patch on the tongue, which helps distinguish it from the spotted bass.


Although the largemouth bass can live up to 15 years, the average life span varies; these fish seldom live more than 10 years. Throughout their range, largemouth bass encountered by anglers average 1 to 1.5 pounds (10 to 13 inches) but are commonly caught up to 5 pounds and less commonly from 7 to 10 pounds.

The maximum size attainable may be 25 pounds, but this has not been proven, and only about a dozen bass in the 20-pound class are known to have been caught. The largest specimen is the all-tackle world record of 22 pounds, 4 ounces, caught from Montgomery Lake, Georgia, in 1932.

Life history/Behavior

Largemouth bass spawn from late winter to late spring; the timing depends on latitude and temperature. Southern populations spawn earliest, and most northern populations latest. They begin to spawn about the time the water temperature reaches 60°F. Fish of about 10 to 12 inches are mature enough to reproduce for the first time.

The male selects and prepares the nest site, a circular bed usually in 1 to 4 feet of water, often positioned near or including some type of object along the shoreline. The female is nudged to the nest site by the male, deposits her eggs, and leaves; the male guards the eggs, which hatch in a few days, and then guards the young fry for a short period.

Growth rates for largemouth bass are extremely variable, influenced as they are by broad geographical location (north versus south), the specific body of water they inhabit within a particular region, and individual differences even within the same population. Despite these influences, bass are capable of growing quickly under the right circumstances.

Food and feeding habits Adult bass predominantly eat other fish, including gizzard shad, threadfin shad, golden shiners, bluegills and other sunfish, small catfish, and many other small species, plus crayfish. They are extremely opportunistic, however, and they may consume snakes, frogs, salamanders, mice, and other creatures.

As aggressive predators, bass primarily are ambush feeders, but they may pursue fish in open water, where there are no ambush opportunities. In normally warm waters, digestion occurs fairly quickly; however, at extremely warm or cold temperatures digestion actually slows, causing the bass to feed less frequently and making them less susceptible to anglers.

Bass are well known for their ability to locate prey in turbid water and at night. Although they are primarily sight feeders when water clarity permits, they otherwise use their highly developed lateral line to detect vibrations and locate prey. They can also detect odors, but their senses of smell and taste are poorly understood by scientists and evidently used less for feeding than are their senses of sight or hearing.

Other Names

black bass, largemouth, bigmouth, linesides, Oswego bass, green bass, green trout, Florida bass, Florida largemouth, southern largemouth, northern largemouth; French: achigan à grande bouche; German: forellenbarsch; Italian: persico trota; Japanese: okuchibasu; Portuguese: achiga.


The largemouth bass is endemic only to North America, and its native range was generally the eastern half of the United States and southern-most Ontario and Quebec in Canada. Since the late 1800s, its range has been expanded to include major or minor portions of every state in the United States, except Alaska, and most of the southern fringes of Canada, as well as numerous countries in Europe, Asia, Africa, South America, Central America, and the Caribbean.


The largemouth bass is typically described as a fish that frequents the weedy sections of ponds and lakes. In reality, the largemouth is highly adaptable to many environments and to many places within various types of water.

These bass inhabit creeks, ditches, sloughs, canals, and many little potholes that have the right cover and forage, but they live principally in reservoirs, lakes, ponds, and medium to large rivers, and not always in the weedy sections.

More specifically, however, they orient toward cover and find most of their food in or near some form of cover. Favored haunts include logs, stumps, lily pads, brush, weed and grassbeds, bushes, docks, fencerows, standing timber, bridge pilings, rocky shores, boulders, points, weedline edges, stone walls, creekbeds, roadbeds, ledgelike dropoffs, humps, shoals, and islands. Although much bass cover is nearshore, some bass do spend time away from shore, especially in unvegetated lakes.

Largemouth bass are most active in waters ranging from 65° to 85°F; the lower 70s is likely optimum. Yet they do well in temperatures much higher and lower, including waters that touch the 90°F mark, as well as frozen lakes that dip to the mid-30s.