Latin name

Semotilus atromaculatus

Other names

Horned dace, common chub, brook chub, mud chub.

Identification

The chub's snout is pointed, the mouth large, with a small antenna at the corner of each jaw, sometimes hidden between the upper and lower jaws. The body is stocky, the back olive-brown, the sides silvery with purplish highlights and the underside whitish. Juveniles have a blackish stripe down the back and a black spot on the tail. Adults also have a dorsal stripe, but the black spot on the tail is faint or absent. There is a large black spot on the front of the dorsal fin. The breeding male takes on an orange hue, as well as 4-8 large, spike-like tubercles (hence the name 'creek chub') on the operculum, body scales and fins. Occasionally the chub may appear mottled with black sand, but this is the result of being heavily infested with the parasite that causes black spot disease (which is harmless to the fish and not transmissible to humans) rather than a natural colouration. Other characteristics include a full lateral line with 47-65 scales, 8 anal rays, 8 dorsal rays and a 2-5-4-2 formula (2 teeth in the lower rows and 4 or 5 teeth in the upper rows). The Sgeek Chub can be distinguished from the Pearl Dace (Semotilus margarita, also known as Margariscus margarita) by its larger mouth. Fallfish (Semotilus corporalis) is a fish that is very similar to the chub, but with larger scales, larger eyes and no black spot on the dorsal fin.

Distribution

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

Habitat

These fish prefer cool, clear water in pools and channels in streams and rivers with gravel bottoms. In dry weather and low water they can survive in isolated pools. They are rare in lakes. Some ichthyologists call the brook chub the "king of the headwaters" because it is often the largest fish found in very small streams. The largest specimens are usually found in deeper waters. The chub is tolerant of some pollution and can be abundant in urban streams.

Size

The maximum length of a creek chub can reach 6 to 12 inches, depending on habitat conditions. The average length is between 4 and 6 inches. Adult males grow faster than females, so the largest chub are usually males. They can live up to 7 years.

Life history and Behavior

Creek chub are pit-breeding spawners that build their gravel nests in channels and downstream watercourses. Nesting and spawning takes place from March to June with water temperatures ranging from 54° to 68°F. It has an interesting spawning ritual that begins in the spring when the male digs a hole in the bottom of the stream and takes out pieces of gravel with his mouth. He carefully guards the hole where he will spawn and attract the female. During the breeding season, adult males are territorial and can be seen swimming in parallel, stalking each other and bumping into each other with their knobby heads. Some males will attempt to spawn in nests built by other males. Spawning occurs when the male wraps his body around the female and the eggs emerge above the nest. A single female can produce more than 7,000 eggs, but only a fraction of these are released during a single spawning session. Females can often be seen swimming belly up for a few seconds after spawning. They recover quickly and are able to spawn again.

Food and feeding habits

Creek chub are omnivorous and feed on a variety of foods including zooplankton, aquatic and terrestrial insects, crayfish, molluscs, frogs and fish. Adults have been shown to consume mainly fish, including juveniles of their own species.

Reproduction

No information