Over the last few decades there has been a major increase in the use of water which has lead to the construction of many hydropower plants. Along with that, the river continuity was interrupted and fish movement became limited causing that some species have become nearly extinct from some rivers during the last century which, in the end, leads to eviromental degradation which can possibly affect human well being and health. One solution in preventing those scenarious could be the implementation of safe and easily found fish passages through the obstruction. For that purpose, work and cooperation of scientific experts in the related fields of study, such as biologists and engineers, is required for the maintenance of a sustainable ecosystem. This work will investigate, evaluate and optimize fish protection and downstream migration facilities by testing the efficiency of the "flexible fish fence". The concept of the flexible fish fence was invented and designed at the Unit of Hydraulic Engineering of the University of Innsbruck, Austria, as a combination of both physical and behavioral method of fish guidance Experiments were conducted with fish under different hydraulic conditions while testing the impact of the angle of the barrier and the distance between the cables. The experiments were conducted at the study facility HyTEC in Lunz am See, Austria. Preliminary experiments, where they tested the basic functions, were carried out previously in the hydraulic laboratory of the University of Innsbruck, Austria. The tested fish species were from the family Salmonidae, which were caught by electrofishing in the nerby rivers Ois and Lunzer Seebach to match the local ecosystem characteristics. 40 experiments were carried out and three different configurations of the fence were tested. Fish were tagged with a PIT tag and their movement was monitored by antennas and video surveillance. The results of the experiments have been analyzed and later discussed, taking into account the influence of the inclination of the screen (toward the bypass) to the guidance of the fish, the influence of the bar clearance on the fish passage through the screen and the overall efficiency of the fish passage.