58 UNIVERSITY OF COLORADO STUDIES 



Body elongate, subterete, not strongly compressed; head large, rather conical, 

 its length exceeding the greatest depth of the body; depth 4.7 (young) to 4, 

 head 3 . 2 to 3 . 9 in the length to the base of the caudal; eye rather large, 2 in the 

 snout, s to 7 in the head and 2. 5 to 3 in the interorbital distance; mouth large, 

 terminal and somewhat oblique; angle of the mouth barely reaching the level of 

 the anterior margin of the eye; maxillary barbel present, quite small, often very 

 obscure in the young, placed on the upper, outer surface of the upper jaw just 

 above the junction of the two jaws, the free portion of the barbel dropping back- 

 ward and downward into the groove at the junction of the two jaws; nostril 

 large and prominent, septum much elevated; dorsal fin short and high, of 8, 

 rarely 9 rays, base of the first ray distinctly posterior to the level of the ventrals; 

 pectorals short, not reaching the ventrals by about half the length of the latter; 

 ventrals not reaching the anal opening; anal fin short, of 8 rays; least depth of 

 the caudal peduncle 3 or a little less in the head, caudal broad and moderately 

 forked; scales 10 or 11, 55-70, 5 to 7; lateral line complete, strongly decurved 

 in the pectoral region ; size moderately large, average adults about 8 inches, large 

 specimens reaching the length of 12 inches. 



Color above dusky to quite dark with a bluish or greenish cast dorsally; 

 below the lateral line almost white with a yellowish or pinkish cast shading to 

 pearly white on the ventral surface between the pectorals; a rather indistinct 

 dusky stripe from the tip of the snout crossing the side of the head and the oper- 

 culum at the level of the eye and continuing along the side of the body as a dusky 

 or blackish lateral stripe, extending to the base of the caudal where it terminates 

 in a distinct caudal spot ; this stripe and spot quite prominent in the young, but 

 often rather indistinct in the adults, the stripe breaking up into a suffuse lateral 

 band or entirely wanting; a rather distinct dusky or black spot covers the bases 

 of the first three or four rays of the dorsal fin, fins otherwise hyaline, the rays some- 

 what outlined with dusky; sides of the body and axils of the pectoral and ventral 

 fins in breeding males with more or less rose-red. 



The larger individuals of Semotilus atromaculatus are used for food, although 

 the Chub is not greatly esteemed as a food fish. Because of the hardiness of this 

 species it is generally considered one of the best live baits for bass and wall-eyed 

 pike. The common Chub ranges over most of the United States east of the Rocky 

 Mountains, in Colorado being quite abundant in the plains streams of the eastern 

 part of the state. The chub is an active, vigorous fish and will often provide 

 considerable sport when hooked, fighting much like some of the game fishes. The 

 larger individuals congregate in the deeper pools of the small streams while the 

 small specimens are found in the more shallow and weedy portions with the small 

 species of minnows. The adult chub is a voracious fish feeding upon surface 

 insects, aquatic insects, small fishes and even the spawn of other fishes. Not 

 infrequently this species feeds upon vegetable matter. The Chub spawns in late 



