Family PERCOPSIDAE 



THE TROUTPERCH FAMILY 



These fishes have elongate bodies, which are rather heavy anteriorly 

 and compressed posteriorly. The head is rather pointed, the mouth 

 small, the eye large, and the maxillary bones small. The premaxillaries 

 border the upper jaw. which is protractile. The jaws are set with weak 

 teeth. The gill-membranes are free from the isthmus; the pseudo- 

 branchiae are developed. The branchiostegal rays number 6. The gill- 

 rakers are tuberclelike. The bones of the head are cavernous; the scales 

 are ctenoid; the lateral line is present. This family contains but two 

 genera — Columbia, found in the Columbia River basin, and Percopsis, 

 found in eastern North America. 



GENUS Percopsis Agassiz 



This genus contains only one species, the troutperch, Percopsis omis- 

 comaycus (Walbaum) . 



TROUTPERCH 



Percopsis omiscomaycus (Walbaum) 



Although this fish (Figure 34) bears a general superficial resemblance 

 to a perch or to a small walleye, it may be distinguished from these 

 species by the presence of an adipose fin somewhat like that of a trout 

 or whitefish. When freshly caught from the water it has a peculiar trans- 

 lucent appearance and is more or less mottled with light and dark colors, 

 with many small blackish spots on and above the lateral line. The head 

 is conical and is free from scales. The head is contained 3.8 times in the 

 length and the depth 4.3 times. The dorsal fin is inserted about the 

 middle of the body and has 2 spines and 9 soft rays. The anal fin has 1 

 spine and 7 soft rays. The ventral fins each have 1 spine and 8 soft 

 rays. There are about 50 scales in the lateral line. This species reaches 

 a length of 8 inches. 



The troutperch ranges from Alberta to Quebec and southward to 

 Kansas, Missouri, Kentucky, and Virginia. Greene (1935) reported it 

 from only a few widely scattered areas of Wisconsin. This species occurs 

 in large numbers in many of the clear, deep-water lakes and larger 

 streams of Minnesota, Avhere it forms no inconsiderable amount of food 

 for the larger game fishes. A large number of specimens have been col- 

 lected in the streams and lakes of the Upper Mississippi and from many 

 places in southern Minnesota. Cox (1897) reported taking five hun- 

 dred specimens at one haul with a small seine in the St. Louis River 



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