The river chub inhabits large creeks to small rivers with rapid, cool waters and rocky substrates. It is a robust, rather cylindrical fish with orange-red fins. It has a large, horizontal, and slightly subterminal mouth and a barbel at the tips of the maxillae. The small eyes are remote from the mouth and are situated near the dorsal border of the head. There is a complete lateral line. The sides are covered with relatively large scales that are not crowded anterior to the dorsal fin; breast squamation can vary from naked to scaled. Body circumferential scales number 28-36.
Nuptial males develop swollen heads and become a pinkish-purple color. They develop large nuptial tubercles, primarily on the head between the eyes and the tip of the snout, but tubercles are also present on adult females and subadult or non-nuptial males. These tubercles or their scars or primordia are important diagnostic characteristics for identifying species of Nocomis. Smaller uniserial tubercles develop on dorsal surfaces of pectoral fin rays 2-7 or 8 in nuptial males. River chubs are often taken by anglers and tuberculate males are sometimes termed "hornyheads."

Size: maximum size about 330 mm (13 in.) total length (Lachner and Jenkins 1971) Color: dark olivaceous above to dusky yellowish below; orange-red fins; juveniles with dark lateral line stripe Fins: dorsal fin rays 8; anal fin rays 7; pelvic fin rays 8; pectoral fin rays 15-19; principal caudal fin rays 19 Lateral-line scales: 37-43; predorsal scale rows 16-18 Gill rakers: 7-8; length of longest rakers twice their basal width Vertebrae: 38-41 Pharyngeal teeth: 4,4

River chubs are nest builders, with males constructing and defending large, shallow, depressions in gravel areas in the stream bed. Nests are lined with pebbles carried to the site in the mouth of the male. Spawning occurs during late spring in Tennessee. Lachner (1952) studied populations of river chubs in New York and found that fecundity of females probably ranges from 500-1,000 ova, and that females spawn in the nests of several different males over a season. Nocomis nests are frequently used as spawning sites for other smaller stream cyprinids (e.g., Clinostomus funduloides, Notropis micropteryx, N. leuciodus, and species of Lythrurus and Phoxinus). Hybrids are known between the river chub and these other communal spawners (Campostoma anomalum, Clinostomus funduloides, and Luxilus chrysocephalus).

Young attain a standard length of about 60 mm (2.4 in.) the first year and reach 95-110 mm (3.7-4.3 in.) in the second year. In the New York populations, sexual maturity was reached in the second year. After sexual maturity, males grew more rapidly than females and attained a larger size. Males and females, respectively, averaged about 140 mm (5.5 in.) and 120 mm (4.7 in.) standard length at age 3 and 180 mm (7.1 in.) and 130 mm (5.1 in.) standard length at age 4. Maximum life span is 5 years. Southern populations may grow more rapidly and be shorter lived. Lachner and Jenkins (1971) reported maximum size in eastern populations to be 270 mm (10.6 in.) standard length. It is likely that extremely large males might be 5 or 6 years old. Adult river chubs feed primarily on aquatic insects.

The river chub is widespread and abundant in all streams in the Park, except the Pigeon River; it occurs up to elevations of about 2,800 ft (Simbeck 1990).

In Park: Nocomis micropogon has no special status in the Park.

References:

Etnier, David A. and Wayne C. Starnes. 1993. The Fishes of Tennessee. University of Tennessee Press. Knoxville, Tennessee.

P. W. Shute, pers. comm., Leader, TVA Natural Heritage Project (February 27, 2001).

Lachner, E. A. 1952. Studies of the biology of the cyprinid fishes of the chub genus Nocomis of northeastern United States. Amer. Midl. Nat. 48:433-466.

Lachner, E. A. and R. E. Jenkins. 1971. Systematics, distribution, and evolution of the chub genus Nocomis Girard (Pisces, Cyprinidae) of eastern United States, with descriptions of new species. Smithsonian Contr. Zool. 85:1-97.

Simbeck, Damien J. 1990. Distribution of the Fishes of the Great Smoky Mountains National Park. Master of Science Thesis, University of Tennessee.