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rock bass

rock bass (Ambloplites rupestris) Photo © Engbretson Underwater Photography

Features and Behaviors


The heavy body and large mouth are among the characteristic features of the rock bass. Its upper jaw extends past the middle of its eye. This fish has six anal fin spines and 12 dorsal fin spines. The sides have dark spots arranged in horizontal lines. The back and sides are green while the belly is dirty white. The dorsal, tail and anal fins have light bands and brown blotches. The average size of a rock bass is 11 inches in length and one pound in weight. A rock bass typically lives five to six years.


The rock bass lives in streams with permanent flow, low turbidity, plentiful hiding places and a silt-free bottom. This fish has the ability to change color rapidly. Spawning occurs in spring. The male fans out a nest on the sand or gravel bottom. Nests are not placed in colonies as are those of some of the other sunfishes. The male stays with the nest until the young have dispersed. The rock bass feeds most actively in late evening and early morning, eating insects, fishes and crayfish.

Illinois Range


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Centrarchidae

Illinois Status: common, native