Gymnocephalus Cernua



Lakes, Canals, Rivers

0 - 1 pounds

3" - 10"


Also Known As: Eurasian Ruffe, Blacktail, Pope, Redfin Darter, River Ruffe

About the Ruffe (Gymnocephalus cernua)

The Ruffe is a very small fish with a scaleless head, a perch-like body, and a downward-facing mouth that is large in comparison to its average size of around only 4 to 5 inches in length. They have an olive-brown color with lighter shades on the side that gradients into a pale yellow underside. They have dark spots along the sides that get smaller as they get closer to their underbelly. 

They can be confused with the Yellow Perch and Walleye Perch but what makes them distinct is the absence of dark vertical stripes and the unique conjoined front and dorsal fins. Those joined fins have 12 to 19 sharp spines in the front that help them defend against virtually every predator.

The Ruff is considered an invasive species because they adapt quickly and efficiently to virtually any environment they are introduced to. They have large glassy eyes and efficient senses, which make them excellent evaders and predators. Their fast maturing and reproductive rates, effective defense against predators, and taste for fish larvae and eggs can easily make them the dominant fish in an environment. 


Diet and Size

The Ruffe mature within 2-3 years and have a lifespan of approximately five years. Their diet is very flexible and changes as it matures, leading them to venture into deeper waters to feed as they grow larger. They have shown a preference for microcrustaceans, aquatic fleas, and the benthic larvae of insects and macroinvertebrates. 

The Ruffe is commonly documented at around 4 to 5 inches long, but it can grow up to 9 inches in length and weigh up to 14 ounces. They have a general lifespan of 3 to 6 years.


Interesting facts about the Ruffe

  • Once captured, the Ruffe becomes extremely stiff, spreads its gill covers, and expands its spiny dorsal fins.
  • When wounded, the Ruffe will expel a warning pheromone to caution others of its kind to avoid the area