A fish ladder was built at the former Rastorfer Mill so that not only the water, but also the fish, can pass through the Schwentine, especially in the dammed area. By swimming from pool to pool, the fish can overcome the difference in height that results from the damming of the water in the individual sections of the Schwentine. The fish ladder at the Rastorfer Mill was completed in 2012.
Sea trout and salmon can now swim from the Kiel Fjord through the dams of the Schwentine via various fish ladders (fish ladder at the mouth of the Schwentine, via this fish ladder at the old riverbed of the Schwentine, at the hydroelectric power station I, the former Rastorfer Mill and at the hydroelectric power station II via the impressive Helix tower fish pass) almost to the spring meadow northeast of the village of Bergfeld (Kasseedorf, near Bungsberg).