As its name implies, this bass has a large month, the maxillary extending beyond the center of the eye, even in small specimens. This is one of the most popular spiny-rayed fish in Washington. Introduced into Washington and Oregon in 1890-95 by the U.S. Bureau of Fisheries, the largmouth has extended its range northward into British Columbia, probably via river systems and unauthorized transplanting.
Largemouths are tolerant of warm water and do best in sallow, weedy lakes and backwaters of rivers.
They prefer clean water with bottoms of mud, sand and organic materials, which provide the best substrate for aquatic vegetation. In Lake Washington they are often found beneath undercut banks during the daylight hours. At night they move into open water to feed, but return to cover during the day. Temperatures of about 80 degrees F. Appear to be optimal for growth and well-being of largemouth bass. They seem to grow faster in the lakes of eastern Washington then in those of western Washington.