bluish-gray body dorsally blending into silvery blue sides fading into white or yellowish on the belly, humpbacked appearance with small sub-terminal mouth, maximum size is around 40 pounds
greatest abundance in the Mississippi and Missouri rivers and their large tributaries, occur rarely in the natural lakes
opportunistic feeders consuming aquatic insect larvae, attached algae, detritus, and zooplankton
Smallmouth buffalo are found in greatest abundance in the Mississippi and Missouri rivers, where it is widely distributed in all reaches. At one time this species was rare in all Iowa water, surpassed in occurrence by both black and bigmouth buffaloes. In recent years its abundance has increased to the point where it currently is equal to the latter species, and it is far more abundant than black buffalo. Smallmouth buffalo occur rarely in the large interior streams and the natural lakes, specifically the Okoboji`s and Spirit Lake.
The smallmouth buffalo prefers habitats in moderate to swift current in clear, deep stretches over substrates comprised of sand, gravel or a mixture of these with silt. It frequents sunken rip-rap structures and scour holes around wing dams in the Mississippi and Missouri rivers. Often it is found in large schools along with bigmouth buffalo.
Body color of the smallmouth buffalo is bluish-gray dorsally blending into silvery-blue sides, fading into white or yellowish on the belly. The body is compressed, and the back is grossly elevated giving a humpbacked appearance. The mouth is small in size, sub-terminal, nearly horizontal and protracts distinctly downward. The head is small and compressed with thick strongly-grooved lips. The lateral line is complete with 36 to 38 large scales. The dorsal fin is sickle-shaped with 26 to 31 fin rays. The anal fin has 9 rays, and the pelvic fins have 9 to 11 rays. Breeding males darken to a sheen of gun-metal blue and develop small tubercules over the body, giving them physical features similar to black buffalo. They also hybridize with the other buffaloes. Being the smallest of the buffalofish, adults will average about 2 pounds at 15 inches in length, 5 pounds at 20 inches, and 10 pounds at 26 inches. Maximum size is around 40 pounds.
Spawning occurs in late April or June at water temperatures of 60 to 65 degrees F. Maturity varies, but most are sexually mature and spawn in the third year of life. Spawning activity occurs over shallow water from 4 to 10 feet in depth in slow to moderate current as the fish congregate in large schools. Often the spawning grounds are found over submerged gravel or sand bars that are adjacent to river channels. Eggs are broadcast at random, fertilized by several males and sink to the bottom where they adhere to any object. Incubation lasts 8 to 14 days. Fecundity of an age II female is 18,200 eggs. Growth of specimens from Pool 10 of the Mississippi River was 4.4 inches at age I, 9.6 at II, 13.6 at III, 15.4 at IV, 16.9 at V, and 18.2 at VI.
Smallmouth buffalo are opportunistic feeders and consume a variety of food items from season to season. Stomach content samples indicate that it is primarily a bottom feeder foraging on a variety of aquatic insect larvae, attached algae, detritus and zooplankton.