The smallmouth bass is a popular freshwater game fish known for its spirited fight. Identifying a smallmouth bass involves observing several key physical characteristics that distinguish it from similar species.
Distinctive Physical Features
Smallmouth bass have a torpedo- or oval-shaped body, aiding swift movement. Their coloration ranges from bronze to brownish-green on the back, fading to lighter yellow or white on the belly. Sides often display eight to sixteen darker vertical bands or blotches, varying in prominence. Unlike some other bass species, the smallmouth lacks a distinct horizontal stripe along its lateral line.
A primary feature is its mouth and jaw structure. When closed, the upper jaw (maxillary) does not extend beyond the back of the eye, giving the fish its “smallmouth” name. The dorsal fin is continuous, with a shallow notch separating the spiny front from the softer-rayed rear. Smallmouth bass also often have reddish or orangish eyes. Scales are present at the base of both the soft dorsal and anal fins.
Comparing Smallmouth to Other Bass
Distinguishing smallmouth bass from similar species, especially largemouth and spotted bass, requires observing specific features. The most common comparison is with the largemouth bass. The key difference is jaw extension: a largemouth’s upper jaw extends noticeably beyond the back of its eye when closed, while a smallmouth’s jaw aligns with or just reaches the middle of the eye. Largemouth bass also have a prominent dark horizontal stripe, unlike the smallmouth’s vertical bars. Their dorsal fin has a deeper separation, sometimes appearing as two distinct fins, unlike the smallmouth’s shallowly notched, continuous fin.
When differentiating from spotted bass, jaw extension can be similar, as both have an upper jaw that does not extend far beyond the eye. However, spotted bass have a distinct patch of teeth on their tongue; smallmouth bass do not. Spotted bass also display rows of small, dark spots along their lower sides, often forming horizontal streaks, differing from the smallmouth’s vertical bars or blotches.
Where Smallmouth Bass Are Found
Beyond physical traits, habitat provides clues for identification. Smallmouth bass thrive in cooler, clearer freshwater environments. They are found in rocky streams, rivers with moderate currents, and large, clear lakes and reservoirs. These fish prefer areas with gravel, rock, and sandy bottoms, often near submerged logs, boulders, or other structures that provide cover.
Their preference for cooler water temperatures (ideally 60-70°F for spawning) contrasts with warmer water habitats favored by largemouth bass. Native to eastern and central North America, smallmouth bass are found throughout the St. Lawrence River and Great Lakes system, extending south to Tennessee and Mississippi, and west to Oklahoma. Through stocking, their distribution has expanded significantly across cool-water tributaries and lakes in Canada and the United States.