Iowa DNR
River & Stream Biological Monitoring
Fish and Benthic Macroinvertebrate Surveys
Physical Habitat Assessments

Rock Bass Ambloplites rupestris

Centrarchidae (Sunfish)
Trophic Class
Top Carnivore
Is Exotic to Iowa?
Is Lithophilous Spawner?
Is Hybrid?
State Listing Status
Not Listed
Assessment Program Statistics

This species was found at 95 bioassessment sites, 3 rapid fish bioassessment sites, 67 fisheries assessment sites, and 0 fisheries presence-only assessment sites. In total, it was collected at 159 distinct sites, or 11.5% of the 1385 total sites monitored by the bioassessment program. It is the 39th most commonly collected species.

The Rock Bass was collected in 216 bioassessment sampling sessions and 322 fisheries assessment sessions. It was present in 3 rapid bioassessment sessions and 0 presence-only sessions.

The biological assessment program has collected a total of 7,934 individual Rock Bass specimens, ranking it the #34 most collected fish.

Species Characteristics

A stout, heavy-bodied sunfish with a large mouth, which extends beyond mid-eye when the mouth is closed. The spiny dorsal fin and soft dorsal fin are broadly connected, but without a notch. The dorsal fin is much longer and more noticeable than the anal fin. Six anal fin spines and 12 dorsal fin spines distinguish this fish from all other sunfish. The body is olive with brassy reflections and dark mottlings along the sides. The breast and belly are whitish, and the lower side has spots that form horizontal lines. There is brown mottling and faint banding on the anal, dorsal and tail fins. The pectoral fins are rounded, set low and are amber-colored.

Species Distribution Maps

HUC12 watersheds where this species has been found