[2] It has been introduced into the Great Lakes of North America, reportedly with unfortunate results, as it is invasive and is reproducing faster than other species.

Its common names are ambiguous – "ruffe" may refer to any local member of its genus Gymnocephalus, which as a whole is native to Eurasia.

It has been introduced to parts of Western Europe (France, northern Italy) and Greece, as well as to the North American Great Lakes.

[1] In Eurasia, the ruffe diet mainly consists of zoobenthos: chironomids,[6] small aquatic bugs and larvae,[7] which are all found in the benthic zone of the water column.

The primary spawning season for the ruffe occurs from the middle of April through approximately June.

One week after the hatching, the young ruffe start to swim and feed actively; they do not form schools at this age.

The ruffe also has an exceptional ability to detect water vibrations through organs called neuromasts.

They suggest that the fish was introduced to the lake via ballast water that was dumped into the Duluth, Minnesota, harbor by anchored freight ships.

Ever since the ruffe was introduced into the Great Lakes system, scientists and fishery managers have been searching for the right way to get rid of them.

In the beginning, the main method of control was to increase the Walleye and Northern Pike populations, because they are natural predators of the ruffe.

Scientists have concluded three things: Ruffe were first discovered in Loch Lomond, Scotland, in 1982, probably introduced as live bait by pike anglers.

Ruffe became the principal food item for the three main fish predators found in the area: the great cormorant, grey heron and northern pike.