Creek Chub (Semotilus atromaculatus)


The creek chub is one of the largest chub and a member of the minnow, or Cyprinidae, family, making it a distant relative to carp. Occurring in great abundance in North America, it is important forage for sportfish, often competes with those larger predators for food, and, because it is hardy and lively, is also a prominent bait used by anglers.

Identification

The snout of the creek chub is pointed and its mouth large, with a single small barbel in the corner of each jaw, sometimes hidden between the maxillary and the premaxillary. The body is stout, colored olive brown on the back, silvery on the sides with shades of iridescent purple, and whitish on the underside.

A juvenile will have a blackish stripe along its back and a black caudal spot; an adult will also have the stripe on its back, but the black caudal spot will be faint or absent. There is a large black spot at the front of the dorsal fin. A breeding male takes on an orange hue, also gaining 4 to 8 large, thornlike tubercles (thus the name “horned dace”) on its opercles, body scales, and fins.

The creek chub may occasionally appear to be speckled with black sand, but this is the result of being heavily covered with the parasite that causes black spot disease (which is harmless to the fish and is not transmittable to humans) and not as a result of natural coloring.

Other characteristics include a complete lateral line with 47 to 65 scales, 8 anal fin rays, 8 dorsal fin rays, and a pharyngeal tooth count formula of 2-5-4-2 (2 teeth in minor rows and 4 or 5 teeth in major rows).

The creek chub can be distinguished from the pearl dace (Semotilus margarita, a.k.a. Margariscus margarita) by its larger mouth. The fallfish (Semotilus corporalis) is a strikingly similar fish to the creek chub, but with larger scales and larger eyes and without a black spot on the dorsal fin.

Size/Age

The creek chub can attain a maximum length of between 6 and 12 inches, depending on its environment; the average is 4 to 6 inches long. Adult males grow faster than females do, and the largest creek chub are usually male. They can live up to 7 years.

Spawning behavior

Creek chub are pit-ridge spawners that build their gravel nests in runs and the downstream sections of pools. Nest building and spawning occur between March and June, in water temperatures ranging from 54° to 68°F. Creek chub have an interesting spawning ritual, which begins in the spring when the male digs a pit in the stream bottom by removing bits of gravel with his mouth.

He carefully guards the pit where the spawning occurs and attracts a female. Adult males are territorial during the breeding season and can be observed swimming in parallel, chasing each other, and ramming their tuberculate heads against each other. Some males attempt to spawn over the nests built by other males.

Spawning occurs when the male wraps his body around the female and eggs are released over the nest. A single female can produce more than 7,000 eggs, but only a portion of these are released during a single spawning event. Females are often observed floating belly up for a few seconds after spawning. They quickly recover and can spawn again.

Food

Creek chub are omnivores that feed on a variety of foods, including zooplankton, aquatic and terrestrial insects, crayfish, mollusks, frogs, and fish. Adult creek chub have been shown to primarily consume fish, including the young of their own species.

Other Names

horned dace, common chub, brook chub, mud chub.

Distribution

Creek chub are found from the Maritime Provinces of Canada west to Montana and south to Texas and northern Georgia. Their distribution extends throughout the eastern half of southern Canada and the central and eastern United States. They occur in the Atlantic, Canadian, Great Lakes, Gulf Coast, Hudson Bay, and Mississippi drainages.

Habitat

These fish prefer cool, clear water in the gravel-bottomed pools and runs of creeks and streams. In dry weather and during low water, they can survive in isolated pools. They are seldom found in lakes.

Some ichthyologists refer to the creek chub as the “king of the headwaters” because it is often the largest fish found in very small streams. Deeper pools usually contain the largest individuals. Creek chub are tolerant of some pollution and can be abundant in urban streams.

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