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-7- numbers in Aztec Creek, Warm Creek and several other permanent streams (Table 2). It appears to feed primarily on algae and, to a limited extent, aquatic insects. Hwmpbacketl Sucker (Xyrauchen texanus). Although this form is native to the Colorado River, only two immature specimens were collected during the survey. Jonez (1954) found the Humpbacked Sucker to be relatively abundant in Lake Mead, especially in the vicinity of river mouths. In Lake Mead this fish spawns in gravelly areas during March and April. The food consists primarily of algae. Colorado River Squawfish (Ptychochelius lucius). Only one specimen of this species was collected during the survey, a 4-inch fish taken from Trachyte Creek. Although at one time this fish was reported to be common in the Color-~ ado River, its numbers have appeared to decrease in recent years. This may be due in part to the presence of the Channel catfish and other introduced species which would tend to compete with it. The Squawfish is well adapted to lotic environments, but does not appear to do well in reservoirs. Jonez (1954) reports that although it .was commonly found in the lower Colorado River before the construction of Hoover and Davis dams, few, if any, Squaw- fish occur in the impoundments. In the lower Colorado River, squawfish have been known to attain a length of 5 feet and a weight of 80 pounds. It is carniverous and predatory, particularly when large (Simon, 1946). Roundtail Chub (Gila robusta). This fish is also indigenous to the Colorado River. However, only two small specimens were collected in Aztec and Kane Creeks, during the survey. Although primarily a stream fish, Jonez (1954) reports that the Roundtail Cub is present in both Lakes Mead and Mohave, and was, observed spawning in gravelly areas in Lake Mohave in May, 1954• This form appears to feed primarily on insect larvae and small fish. Utah Chub (Gila atraria). Several small cyprinids collected -from a backwater at White Canyon and from Aztec Greek appear to be aberrant members of this species. Although this form is primarily a species of the Bonneville basin, it has doubtlessly been introduced into parts of the Colorado River drainage. Speckled dace (Rhinichthys osculus). This form was abundant in many of the tributary streams, occasionally being the only species of fish present in the tributary. It occurred primarily in schools in clear water, frequenting both the stream and ponds, and was often taken from shallow riffle areas. Fathead Minnow (Pimephales promelas). Although one of the most common fish in the Glen Canyon area, this form had not previously been reported from Utah. This fish was commonly found in both the clear tributary streams and the muddy backwaters formed at the mouths of the canyon. It often frequented areas with muddy bottoms and appeared to tolerate turbid water far better than did the dace. Like the dace, the fathead minnow was often found in schools. Spawning fathead minnows were observed at White Canyon on July 1, 1958, and in Seven Mile Canyon on July 8, 1958, in areas with sandy bottoms.