The dark multi-coloured fish with a big head is called bullhead. The bullhead thrives in flowing waters and surging beaches. As it gets dark in the evening, the bullhead comes out of its hiding place from between rocks and stays there waiting for a suitable prey. When for example an amphipod or an isopod swims by, the bullhead darts after it as quick as lightning. Early in the spring male bullhead prepares a nest between rocks, where it then lures a female to spawn. After spawning the male takes care of the nest until the fry hatch in approximately four weeks time. The bullhead reaches the length of up to ten centimetres (about three inches). It is found on the whole of the Finnish coastline, exclusive of the northernmost Lapland.