<img src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Gymnocephalus_cernuus_P%C3%A4rnu_River_Estonia_2010-01-06.jpg/1280px-Gymnocephalus_cernuus_P%C3%A4rnu_River_Estonia_2010-01-06.jpg" width="500"> From [Wikipedia](https://en.wikipedia.org/wiki/Ruffe) under [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0) license. Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Percidae Genus: Gymnocephalus Species: G. cernua Russian name: Ёрш All species of the genus Ruff have physiological adaptations to life in conditions of a *small amount of light*. Ruffe diet mainly consists of *zoobenthos*: chironomids, small aquatic bugs and larvae, which are all found in the benthic zone of the water column.