Semotilus is the genus of creek chubs, ray-finned fish in the Cyprinidae family. The term "creek chub" is sometimes used for individual species, particularly the common creek chub, S. atromaculatus. The creek chub species of minnows can grow from 6 to 10 inches and resemble the grass carp. They can be found in the United States and Canada in any small stream or creek. They hide under small rocks for protection. They have a small black spot on the dorsal fin for easy identification.