Rock Bass, Ambloplites rupestris
Identifying characteristics: (Native Fish) Two dorsal fins with spinous and soft-rayed portions united, large mouth, six anal spines, red eye, rows of dark dots on sides.
Rock bass are native to fresh water in east-central North America. This heavy bodied member of the sunfish family can be readily distinguished from other similar species by the six spines in the anal fin (other typical sunfishes have only three anal fin spines). These fish are a commercial species in the Great Lakes and are also an important sport fish. They are lively fighters when hooked, and their flesh is firm and delectable.
True to their name, rock bass live in rocky areas in the lake's shallows. Adults live in groups, often associating with smallmouth bass and other similar fish. Spawning takes place in late spring and when water temperatures reach 55 to 60 degrees F. Like other members of the sunfish family, the male digs a nest in the lake shallows, and guards it tenaciously. A spawning area may be heavily used with several nests very close together. As a result, males can become quite aggressive as they attempt to defend territory and attract and hold females. The male guards and fans the eggs, and later broods the young for a short time. Rock bass grow quickly and adults weigh an average of 4 to 8 ounces. An average length is six to eight inches although some rock bass reach 12 inches. Few rock bass live beyond 10 to 12 years.
Large bass, northern pike, muskie, and perhaps walleyes prey on young rock bass. Rock bass compete with smallmouth bass for food. They eat aquatic insects, crayfish, and small fish, including their own young, yellow perch, and minnows. Rock bass occasionally take food from the surface.
Rock bass graphic courtesy of Joseph R. Tomelleri and copyrighted.