Fish Iowa - Fish Species - Largemouth Bass

Characteristics

A slender, streamlined sunfish, with a very large mouth, with the upper jaw extending far past the rear margin of the eye when the mouth is closed (except in small young). The spiny and soft portions of the dorsal fin are almost completely separated by a deep notch. The middle of the green-shaded body has a broad continuous dark stripe, but this sometimes becomes unclear in large adults and fish taken from turbid water. The belly is greenish-white or yellowish, and the eye is usually gold. The pyloric caeca, finger-like extensions at the junction of the stomach and intestine, are forked, and the tail fin in young Largemouth Bass is clearly bicolored -- not tricolored as in Spotted Bass and Smallmouth Bass. The rear part at the fin is much darker than the basal part.

Foods

Fish, frogs, crayfish, aquatic and terrestrial insects, and any small living animal or bird which falls in the water. The small sac fry of bass feed upon microscopic crustaceans. First-food items are supplemented with insects and insect larvae as the fish grows. Largemouth Bass usually start foraging on fish when they are 1- to 2-inches long.

Expert Tip

Bass are usually caught around structure, look for partially submerged trees and boat docks pilings.

Details

Spawning starts in early May and lasts into June when the water temperature is 63 to 68 degreess. They deposit their eggs on the roots of submerged plants or grass over rocky or mud bottoms. Male Largemouth Bass usually build a nest before spawning, but sometimes they will spawn with very little nest preparation. Water depth over nests ranges from 1 to 15 feet, but the normal depth is 1 1/2 to 3 feet.

The eggs, which  vary from 2,000 to 26,000 in each nest, hatch in 3 to 6 days depending on water temperature. Largemouth Bass in Iowa average 4- to 6-inches long during the first year, but lengths of 10- to 12-inches are not unusual in newly stocked lakes and ponds. Total lengths of 8- to 12-inches are expected in the last part of the second year of life, and fish up to 16-inches are common in the third year. Both sexes usually reach sexual maturity in their third year of life, but faster growing bass can mature in the second year. Largemouth Bass have been known to reach 22-pounds in the southern states, but are smaller in Iowa. 

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Learn more about this fish at the Largemouth Bass Profile DNR Homepage

State Record(s)

Patricia Zaerr
May 01, 1984: 10.75 lbs. - 23.50 in.
Lake Fisher

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Master Angler Catches

Keith Dennis
November 22, 2025: 5.36 lbs. - 21.00 in.
Williamson Pond

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Victoria Kinney
November 18, 2025: 5.50 lbs. - 21.50 in.
Kinney Pond

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zach parson
November 16, 2025: 4.60 lbs. - 20.60 in.
Backyard pond

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Howard Kamish
November 13, 2025: 6.10 lbs. - 22.00 in.
Mills County farm pond

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