Fish screens are increasingly being used to prevent fish entrainment at water diversions and intakes. International screen specifications suggest that approach velocities should generally be between ≤ 0.1 and 0.3 m/s to minimise impingement. These specifications are based on the swimming performance of a small range of target fish species, mostly from North America. It is uncertain to what extent these specifications provide protection for a wider range of species. To determine suitable approach velocities for 17 freshwater fish species and two crustacean species, we simulated screen encounters at a 3 mm mesh wedge-wire screen panel in a specialised flume under various approach velocities (ranging from 0 to 0.3 m/s). Fish and crustacean behaviour, including species-specific susceptibility to impingement and entrainment was analysed. Impingement was effectively reduced at velocities ≤ 0.1 m/s for a wide range of fish at different life stages. Approach velocities greater than 0.1 m/s were inappropriate for most of the fish species tested and resulted in impingement. At 0.3 m/s, impingement susceptibility and detachment ability varied across the range of fish and crustacean species tested. Species-specific behaviour such as volitional screen contacts or flow responses played a crucial role in screen encounters and should be considered when designing screens globally to protect aquatic biota.