Fish protection on water intakes has become a major ecological topic during the last decades in most industrialised countries. Some behavioural systems have been developed to scare fish away from water intake, such as light, acoustic, hydrodynamic or electrical systems. Although none of these are completely inefficient, none have shown a convincing multi-specific effect. Characteristics of the various systems will be briefly discussed. Acoustic systems probably have the best potential, but their efficiency depends on signal frequency and fish hearing capacities. Previous tests on Atlantic salmon smolt Salmo salar and the European silver eel Anguilla anguilla have suggested that infrasound is a good candidate as an efficient multi-specific acoustic barrier. Recently, we have tested behavioural responses of cyprinids to infrasound. In Lake Borrevann, Norway, acute fish avoidance responses at a distance up to 10 m from a 16 Hz projector were revealed by echosounding, with no obvious habituation. Two infrasound units were also installed in front of a cooling water intake of a nuclear power plant on the River Meuse, Belgium. We used an echosounder to compare the number of cyprinid fishes entering the intake canal during on-off infrasound sequences. Reduction of fish entering during on-periods varied from 86% 12 m upstream of the units to insignificants reductions 18 m downstream of the units. A significant reduction of 47.9% was observed considering the whole beamed width (54 m) of the intake canal. Our results confirm the potential use of infrasound as an efficient multi-specific, behavioural fish barrier.