smallmouth bass

Smallmouth bass is a common native fish. Its native range extends from southern Quebec to North Dakota and south to northern Alabama, including the St. Lawrence-Great Lakes system, the Hudson Bay (Red River) basin, and the Mississippi River basin, and to Arkansas and Missouri, including the Missouri River and Meramec River basins. It has been intentionally introduced for sportfishing throughout the United States, southern Canada, and other countries.

Smallmouth bass prefer large, clear lakes and clear streams and rivers with abundant cover that provide cool water temperatures in the summer. They are commonly found in streams with moderate flow, overhanging trees, and rocky bottoms. They often congregate around fallen logs and other large debris.

Smallmouth bass adults feed on crayfish, amphibians, insects, and other fish, including the young of other smallmouth bass. The typical lifespan is 6 to 14 years in the wild, but they can live up to 26 years.

The size of an adult fish depends more on its age than its habitat. Smallmouth bass are typically 2½″ to 4″ (6 to 18 cm) in total length after one year, 5½″ to 10½″ (14 to 27 cm) long after two years, 7½″ to 10½″ (19 to 27 cm) long after three years, and 8¼″ to 16″ (21 to 41 cm) long after four years. However, they can live longer and they can get much larger. The record smallmouth bass caught in Minnesota weighed 8 pounds and was caught in West Battle Lake in Otter Tail County in 1948. The length of the fish was not recorded. More recent Minnesota smallmouth bass records, particularly for catch-and-release, do include weight measurements. For example, a 22¾″ smallmouth bass was recently certified as a catch-and-release record from Basswood Lake in Lake County.

The mouth is large, but the upper jaw extends only to about even with the pupil of the eye. The eyes are reddish. Three dark bands on the side of the head radiate from the eyes and mouth. There are 14 or more rows of scales on the cheeks. They are smaller than the scales on the bony flap that protects the gills (operculum).

The body is tapered at both ends, widest in the middle, and rounded or pointed at the head (fusiform). It is stocky, moderately compressed, and oval in cross section. It is fairly streamlined for a bass. The body color is greenish brown to bronze above, grading continuously to gray or yellowish white below. There are no horizontal stripes on the sides, but there are often 9 to 16 faint, dark, vertical bars.

The dorsal fin is distinctly divided. The front portion has 9 or 10 spines and is only slightly rounded. It is broadly joined to the softer rear portion, which has 13 to 15 rays. The anal fin has 3 spines and 10 to 12 rays. The pectoral fins have 16 to 18 rays. The row of pores that runs from the gills to the tail (lateral line) is faint but visible. There are 66 to 78 scales on the lateral line.

Typical total length

1 year old: 2½″ to 4″ (6 to 18 cm)

2 year old: 5½″ to 10½″ (14 to 27 cm)

3 year old: 7½″ to 10½″ (19 to 27 cm)

4 year old: 8¼″ to 16″ (21 to 41 cm)

Large, clear lakes and clear streams and rivers

6 to 14 years

Crayfish, amphibians, insects, and other fish

Sources

24, 29, 30.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu, 6/15/2025).

Nonindigenous Aquatic Species (NAS) information resource for the United States Geological Survey

Mundahl, N.D. 1994. Distribution of fish species within ten watersheds in southeastern Minnesota. Final report submitted to the Minnesota Department of Natural Resources. Unpaged.

Common

The taxonomy of fishes above the rank of order is in flux, and it seems that no two sources agree. ITIS does not agree with Catalogue of Life, and neither agree with iNaturalist. Wikipedia is inconsistent – it does not even agree with itself. MinnesotaSeasons will follow the ranking of Catalogue of Life for the higher level (supraordinal) taxonomy.

The Smallmouth Bass

Caught and released this am. Within the city limits of Rochester MN. Zumbro River.

? Smallmouth?

Scuba diving with Smallmouth Bass (Micropterus dolomieu) in Northern Ontario
Planet Neat

North Maine Woods Smallmouth
Fish’n Cam

Gregory Gilman
7/31/2025

Location: Rochester MN

? Smallmouth?

Gregory Gilman
6/10/2025

Location: Rochester MN

Caught and released this am. Within the city limits of Rochester MN. Zumbro River.