The back and sides are pale olive or straw-colored and the belly whitish. There are two longitudinal rows of dark spots along either side and a single mid-dorsal row.
The trout-perch is an uncommon but widespread inhabitant of the upper Mississippi River, the Thompson Fork of the Grand River and Chariton River in southcentral Iowa. It also inhabits some of the natural lakes of Dickinson County and the Big Sioux River and its tributaries in northwest Iowa.
aquatic insects and other small invertebrates
State Records are not documented for non-game species.
Trout-perch populations can be found in scattered locations in Iowa. It is uncommon but widespread in the Mississippi River. Trout-perch have been found in the Grand and Chariton river watersheds in southern Iowa. And in the extreme northwest corner of the state, trout-perch have been collected in the large rivers such as the Big Sioux and Rock rivers as well as some of the natural lakes. The trout-perch inhabits low-gradient streams with high water quality as well as clear lakes with clean sand and gravel bottoms, where it can be found at depths of almost 200 ft. In streams, the trout-perch prefers long, deep pools with sand and fine gravel substrates. Researchers have found, however, that the trout-perch reaches its greatest abundance over bottoms of organic debris such as detritus and leaves. The trout-perch is extremely intolerant of clayey silt deposition and avoids rooted aquatic vegetation and mud-filled bays in lake habitats. Stream channelization, increased siltation and turbidity have most likely lead to the recent decline of this species.
Trout-perch are thick-bodied, translucent-appearing fish. The mouth is horizontal and large with the upper jaw not reaching beyond the front of the eye. The tail fin is deeply forked and a fleshy adipose fin is present. The single dorsal fin has two weak spines and 10 to 11 rays. The anal fin has a single weak spine and 6 to 7 rays, and the pelvic fin one spine with 8 to 9 rays. A lateral line is present and contains 47 to 58 scales. The back and sides are pale olive or straw-colored and the belly whitish. There are two longitudinal rows of dark spots along either side and a single mid-dorsal row. Adults are commonly 3 to 5 inches in length.
In physical appearance this fish resembles both a trout and a perch. It has the adipose fin and naked head of the Salmonids but the ctenoid scales, fin spines, and mouth shape similar to Percids. The fish is nocturnally active in the shallows, foraging along the bottom for aquatic insects and other small invertebrates. During the daylight it moves into deep water or hides around structure. The trout-perch spawns from May through August in shallow water over sand and gravel, and adults sometimes migrate from lakes habitats to shallow tributaries for spawning. They are random spawners, and no parental care is given to the eggs or fry. Females reach a larger size than males, and their life span is 4 to 5 years. The trout-perch is a major source of food for many game fish in our northern natural lakes.
Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.
Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.
Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames
Photo credit: Photo courtesy of Konrad P. Schmidt, copyright Konrad P. Schmidt.