In Norway there are built nearly 400 fish ladders. Most of the fish ladders are the pool type or the weir type fish ladder. The largest fishway in Norway is situated in Mattiselva in the north of Norway. The total fall is about 45 m. The fish ladder is 500 m long and consists of 105 pools. Most of the fish ladders are built in order to help salmon and sea trout up in the rivers. About 70 of the fish ladders are built for brown trout, grayling, or white fish.