Ruffe (Gymnocephalus cernuus)

Length: 4 to 6 inches (25 cm)
Coloring: olive-brown to golden-brown on back, paler on the sides with yellowish white undersides
Common Names: Eurasian ruffe, river ruffe, pope
Found in Lakes: Huron and Superior
The ruffe is a small but aggressive fish native to Eurasia. It was introduced into Lake Superior's Duluth/Superior harbor area in the mid-1980s in the ballast water of an trans-oceanic ship.
In Europe, the ruffe generally matures in two or three years, but it may mature in one year in warmer waters. It spawns between mid-April and July, depending on location, water temperature and preferred years.

The ruffe starts reproducing at age two or three but can reproduce after the first year in warmer waters. An average female can produce 130,00 to 200,000 eggs per season.

A relative of the perch, the ruffe spends its days in deeper water and moves to the shallows to feed at night. To avoid predators, the ruffe prefers darkness, and uses spe