Trout-perch

Trout-perch, photo courtesy of Konrad P. Schmidt, copyright Konrad P. Schmidt

Characteristics

A thick-bodied, translucent-looking fish. This fish looks like 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 mouth is horizontal and large with the upper jaw not reaching beyond the front of the eye. The tail fin is deeply forked with a fleshy adipose fin. 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 has one spine with 8 to 9 rays. A lateral line is present with 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 long.

Distribution

Trout-perch Distribution

Uncommon but widespread in the upper Mississippi River, the Thompson Fork of the Grand River and Chariton River in south central Iowa. It also lives in some of the natural lakes of Dickinson County and the Big Sioux River and its tributaries in northwest Iowa.

Foods

Aquatic insects and other small invertebrates

State Record

State Records are not documented for non-game species.

Expert Tip

None

Details

Trout-perch live in 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 feet. In streams, trout-perch prefer long, deep pools with sand and fine gravel substrates. Researchers have found that trout-perch reach its greatest abundance over bottoms of organic debris such as detritus and leaves. It is extremely intolerant of clayey silt deposition and avoids rooted aquatic vegetation and mud-filled bays in lakes. Stream channelization, increased siltation and turbidity have most likely led to the recent decline of this species.

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. Trout-perch spawns  from May through August in shallow water over sand and gravel, and adults sometimes migrate from lakes 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.

Sources:

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.


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Present in these Iowa water bodies:
Lake/Stream County Location Acres/Length
Rock River Sioux 55.00