The Eurasian ruffe, Gymnocephalus cernuus, (ruffe) is a freshwater fish native to Eurasia. It is thought to have been transported and accidentally released into the Great Lakes from the ballast water of an ocean-going ship. The ruffe was first reported in in western Lake Superior in 1986 at the St. Louis River harbor. They have since spread within the upper Great Lakes.

Characteristics of ruffe may allow them to compete with native fish species for food and habitat resources.

Learning to identify the ruffe and knowing where they are found are important steps toward preventing or deterring their spread to new areas.

Identifying Characteristics

The ruffe is a member of the perch family and resembles perch in body shape. Identifying characteristics are shown on the image below.

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