The removal of barriers to animal movement has become a priority to improve the ecological status of rivers. However, complete removal of barriers is not always an option. Fishways, such as the Larinier Super-Active Baffle (LSAB), are commonly employed to mitigate the effects of barriers to upstream fish movement. We monitored the upstream passage behaviour and performance of three wild brown trout phenotypes, encompassing a range of sizes, at a LSAB fishway adjacent to a flow-gauging weir, using PIT and Radio telemetry. Fish were captured and tagged 0.4-1.5 km downstream of the weir in the pre-spawning period. Of those that attempted passage of the weir-fishway complex, potamodromous (nattempt =8; nsuccessful =2; χ²1 =8.8, p <0.005) and parr-marked (nattempt =22; nsuccessful =8; χ²1 =4.5, p <0.05) individuals were less successful than expected, but anadromous trout were as successful as expected (nattempt =27; nsuccessful =21; χ²1 =1.3, p >0.05). A significantly greater proportion of anadromous trout traversed the weir than used the fishway (nweir =16; nfishway =5; χ²1 =5.8, p =0.02), with no preference for specific flows for route of passage (fishway =Q3-Q74; weir =Q3-83; t-test: t6.1 =-1.0, p > 0.05). Equal numbers of potamodromous (n=1) and parr-marked (n=4) phenotypes traversed the weir and used the fishway. In each phenotype, one fish failed to ascend the fishway. Although the fishway may facilitate upstream passage, it appears the fishway fails to attract fish. The good passage of anadromous trout is likely due to their greater relative size and swimming performance compared to other phenotypes.