Slender madtom

Slender madtom


The Slender Madtom is yellowish on the sides and darker on back. It has a white to cream belly, a small head, and a narrow and strongly depressed body. There are 14-17 rays in the anal fin. A light colored, bar shaped marking on the back near the head proceeds the dorsal fin.


Slender madtom Distribution

Major tributary streams of Mississippi River, greatest abundance in upper Des Moines River drainage.


Insects, aquatic plants

State Record


Expert Tip



Distribution of the Slender Madtom is limited to the major tributary streams of the Mississippi River, reaching its greatest abundance in the upper Des Moines River drainage. Some scattered collections have been made and the species has been reported in a few man-made lakes. It is not abundant at any location in the state.

The body is yellowish on the sides and somewhat darker on the back. It has a white to cream color belly. The premaxillary band, or tooth patch on the upper jaw, is bar-shaped. The head is small, narrow and strongly depressed. There are 14 to 17 rays in the anal fin. No lateral stripe occurs along the side of the body. A light-colored, bar-shaped marking is on the back near the head and immediately preceding the dorsal fin. The upper jaw is somewhat longer than the lower. It can also be distinguished from the other madtoms by the dark margin on the outer edges of the dorsal, anal and tail fins. It rarely exceeds 4 to 5 inches in length.

Little is known about the life history of the Slender Madtom. It has been speculated that in spawning this fish deposits a small, compact cluster of eggs, probably no more than 100, into a shallow depression that was excavated beneath a flat rock, much like that of other madtoms. Eggs and newly hatched young are guarded by at least one of the parents, presumably the male like most Ictalurids. Slender madtoms live entirely in riffle areas of small or medium size streams.

Present in these Iowa water bodies:
Lake/Stream County Location Acres/Length
Missouri River (Sioux City to Little Sioux) Harrison Chris Larsen Park: 1280 Larsen Park Road/Sioux City, IA. Located on the Sioux City riverfront along the Missouri River. Larsen Park offers 110 acres on the Sioux City Riverfront. Managed by the City of Sioux City. 64.00
Missouri River (Council Bluffs to state line) Fremont Lake Manawa State Park: 1100 South Shore Drive/Council Bluffs, IA 51501 phone: 712-366-0220. Managed by the Iowa Department of Natural Resources Lake Manawa State Park has boat ramps on the Missouri River within the park. 61.00