Vlasina is a river in the southeastern Serbia. Its spring is below the dam of the Vlasina lake. Due to its mountainous environment and lack of industrial pollution, Vlasina is one of the purest rivers in Serbia. In the upper river flow there are a lot of fish like brown trout (Salmo trutta m fario) and gudgeon (gobio gobio). The middle and lower flow there are chub fish(Leuciscus cephalus), Barbel (Barbus Barbus), while only in the lower flow can be found Loach (Misgurnus fossilis). The total length of the river is 68 km.