Gudgeon

Gobio gobio, or the gudgeon, is a species of fish in the family Cyprinidae. This small fish is widely distributed in fresh-water streams and lakes across central and temperate Eurasia. The gudgeon inhabits various fresh-water habitats with sandy bottoms. It is a gregarious species, and feeds on benthic invertebrates. Its life span is up to five years. Gudgeons are usually smaller than 12 cm, rarely over 15 cm long. The common name gudgeon may also refer to other species of fish.

Source: Wikipedia