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Rock Bass (Ambloplites rupestris) - Introduced

14 cm rock bass.

A typical, 6-inch adult rock bass. Note the dark spots on many of the scales along its side.

Identification. Deep-bodied. Large head and mouth that reaches to below center of pupil. Irregular camouflage blotches on sides. Small spots on each scale below the lateral line forming 8-10 faint, narrow bands. Dorsal spines 11-12. Pectoral fins short and rounded. Anal spines 5-7. Base of anal fin shorter than base of dorsal fin. Typically dark brown to olive on back fading to brown, brassy or greenish on sides and lighter on belly. Eye color brown to bright red.

16 cm rock bass.

A darkly-colored 6-inch rock bass.

Size. Commonly 5 to 7 inches. State survey max. size 12.2 inches. Conn. State Record 1.3 pounds. Max. reported size 16.9 inches. World Record 3 pounds.

Distribution. Native range includes the Eastern United States and southern Canada from the Mississippi drainage south to Tennessee, not including most of the Eastern coastal states. Has been introduced into adjacent areas. In Connecticut, rock bass were originally restricted primarily to the western part of the state, but their range has increased into eastern Connecticut, most likely through illegal introductions by anglers. They are typically common where found.

Rock bass distribution map.

All maps created in 2009. See CT DEEP Fish Community Data for updated distributions.

Habits. Prefer lakes and slower-moving areas of streams with rocky bottoms, clear water and moderate to little vegetation. Are often found in shallow water around rocks and are easily caught by angling on a variety of small baits and lures. Rock bass are relatively easy to keep in home aquariums, but are less aggressive than most other sunfish species and often hide behind structures. They can be taught to accept pellets, but need at least some fresh food.

Rock bass light phase in a tank.

The mottling on a rock bass provides excellent camouflage for its rocky habitat.

Comments. Rock bass have relatively large mouths, so are commonly caught by anglers seeking larger gamefish.

6 cm juvenile rock bass.

This 2.3-inch juvenile rock bass has a large eye and mouth, and markings reminiscent of an adult.

 

Text and images adapted from Jacobs, R. P., O'Donnell, E. B., and Connecticut DEEP. (2009). A Pictorial Guide to Freshwater Fishes of Connecticut. Hartford, CT. Available for purchase at the DEEP Store.