Ambloplites rupestrisGoggle eye(Also: Northern rock bass; Redeye; Redeye bass; Rock bass)

Geographic Range

Rock bass are native to the Great Lakes region, the Mississippi Valley, and certain streams on the east side of the Alleghany Mountains. They were imported into Germany and other European countries in 1883.


Rock bass occupy large lakes, reservoirs, and ponds in the midwest and Mississippi Valley, and they are also found in streams east of the Alleghany Mountains. Rock bass, in the winter months, can be found under ice, yet they can stand a summer temperature as high as 88 degrees F. Though sometimes found in muddy bayous and in waters with decaying vegetation, rock bass thrive best in clear, pure waters well stocked with aquatic plants and small crustacea. (Bowers, 1903).

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Adult rock-bass usually weigh between 1/2 and 3/4 pounds, occasionally reaching 1 pound, and they have been recorded to weigh 3 pounds. The young grow slowly, averaging 2 inches in length during the first six months. Their dorsal fin is much larger than the anal, with 11 spines and 10 rays; the anal fin has 6 spines and 10 rays. Adults are olive-green on the top, greenish-silvery on the sides and white on the belly. Young are often blotched with black, while adults have a dark spot at the base of each scale, forming stripes. (Bowers, 1903).

  • Range mass
    0 to 1300 g
    0.00 to 45.81 oz
  • Average mass
    0 g
    0.00 oz


Spawning occurs in spring and early summer, requiring a temperature above 10 degrees celsius. Males make nests in the sand or gravel at a depth of about 1.8 meters. The male cleans the gravel with his caudal fin and tail until every particle is bright. The nest is usually 30 cm in diameter. In the act of spawning, the male and female cross the nest, their stomachs close together, the male a little behind the female, and simultaneously void the eggs and eject the milt. The real act of spawning takes a minute or less. After the female lays the eggs, the male guards the nest. The female may lay 2000 to 10,000 eggs depending on her size. The hatching period takes from one to three weeks. Upon emerging, the young rise in a school and hover over the nest for several days before scattering. The male continues to guard the young during this period. They become sexually mature between 3 and 5 years of age. (Bowers, 1903; Bergman, 1942).



During the winter the rock bass remain in schools. These schools break up in the spring when the males begin the preparation of the nests.

Communication and Perception

Food Habits

The main source of food of this species is aquatic plants. They also feed on small crayfish, minnows, tadpoles, worms, and insects. The food of the young consists of minute animals, mainly crustacea and insects, and also vegetation. Some rock bass become cannibalistic in early life, with the larger eating the smaller. (Bergman, 1942).

Economic Importance for Humans: Positive

All bass are fine game fishes, with tournaments being held regularly. Because there are so many bass fisherman their abundance is vital. The indirect value of bass fishing in rural districts, in the expenses of visiting sportsman is immense. Bass fisherman spend billions of dollars each year on guides, accommodations, gas, outdoor clothing, meals, tackle, bait, boats, motors, and permits. Their contribution to the economy is more than sportsmen spend on football and baseball combined. It is estimated that 85 percent of licensed anglers fish for bass. (Bauer, 1955)

Conservation Status

There are 9 genera and 30 species in the bass and sunfish family. Rock bass are one of the most abundant fish in the United States. Their adaptability to extreme temperatures has made their introduction to new areas easier than most other fishes. They have been successfully introduced into the western states of California, Washington and Utah. They have also been transplanted into England, France, Germany, and Finland. The artificial breeding of rock bass, by taking and impregnating the eggs, has not been successful. The eggs can only be stripped with great difficulty, and it is necessary to kill the male to obtain the milt. Also, obtaining the eggs and milt at the same time is difficult. Interruption or handling, even during spawning, prevents the discharge of eggs or milt. Artificial ponds for bass are very common in the midwest and southern states. The water must be at least 6-10 feet deep. (Bowers, 1903).


Chris Rolf (author), University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


uses touch to communicate


Bauer, E. 1955. Bass in America. New York: Simon and Schuster.

Bergman, R. 1942. Fresh-Water Bass. New York: Penn Publishing Corp..

Bowers, G. 1903. U.S. Fish Manual. Washington D.C.: Government Printing Office.