Gudgeon is a typical bottom fish: it has barbells on both sides of the mouth, and with its downward pointing mouth it looks for insect larvae and other bottom animals. Gudgeon favours muddy and eutrophic waters – it is not found in barren rivers. Gudgeon is the most common fish species in the Porvoo river and the Vantaan river. At best it reaches the length of about 15 centimetres. The French find gudgeon a great treat, but in Finland it has no economic value.