creek chub

​creek chub (Semotilus atromaculatus) Photo © Uland Thomas

The creek chub may attain a length of five to seven inches. The male is larger than the female. Its life span is about four or five years. The creek chub has a cylindrical body. There is a large, black spot at the front base of the dorsal fin. Its mouth reaches past the front edge of the eye. The back is green-brown with a dark stripe down the middle. The green-silver sides have a dark stripe that continues around the snout to the upper lip, and the belly is silver-white. Fins are yellow or light green, and there is a black bar along the back of the gill cover. A small barbel may be present in the groove above the upper lip near each corner of the mouth (but this trait is variable, and the barbel may be absent on one or both sides). The breeding male is colorful with his orange lower fins, orange dorsal fin base, blue side of the head and pink lower half of the head and body. Projections (tubercles) are present on the head and scattered over the remainder of the body and the fins.

The creek chub may be found statewide in Illinois. This fish lives in creeks and small rivers in rocky and sandy pools. It often lives in streams that stop flowing in hot, dry weather when it must survive in isolated pools or die. The species may move back into the stream from downstream when enough water is present again. The adult creek chub hides under or among objects in the water during the day and becomes active at night. Spawning occurs in spring. The male digs a pit in the stream bottom by removing gravel with his mouth. He guards the pit while trying to attract females. Spawning occurs over the pit. The male guards the nest but does allow a few other minnow species to nest there, too. After the eggs are deposited, the male covers them with stones and moves to an adjacent section downstream to dig another pit. By the time spawning is over, there may be a long ridge of gravel containing thousands of eggs. The creek chub is a carnivore, eating whatever it can find, particularly insects, minnows, small fishes, crayfish, worms and mollusks.

Kingdom: Animalia​
Phylum: Chordata​
Class: Actinopterygii​
Order: Cypriniformes​
Family: Leuciscidae