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ruffe (Gymnocephalus cernuus) Photo © Konrad P. Schmidt, University of Minnesota

Features and Behaviors

The ruffe looks somewhat like a yellow perch, but its two dorsal fins are broadly connected instead of separated. The back is green-brown to golden-brown in color, and the belly is yellow-white. The mouth is slightly downturned. This species may reach 10 inches in length. This fish has large sensory pores under the skin on the cheeks and dark spots in the dorsal and caudal fins.

The ruffe eats aquatic insects and their larvae. It is a nonnative species that has been established in Lake Michigan and Lake Superior. It is believed to have been dumped into harbors in the ballast water of ships. It is native to Europe and Asia.

Illinois Range


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

Illinois Status: common, nonnative