Freshwater salinization is an emerging threat impacting one-third of the world's freshwater bodies. However, the salinity tolerance of many inland fishes remains understudied, despite being a crucial factor in determining species distributions and fitness. We analyzed a global database of experimental salinity tolerance of inland fishes, compiled from 128 sources, to investigate geographical and taxonomic biases. Additionally, we examined how salinity tolerance relates to fish traits and how experimental data align with field-reported salinity levels..Experimental data on salinity tolerance was available for less than 1% of the world’s inland fishes, with data severely lacking from diverse tropical regions and orders such as Siluriformes. Most studies focused on relatively large and widely distributed species from North America, Europe and Oceania. Our results showed that fish salinity tolerance was strongly associated with fish habitat type, taxonomy, aspects of morphology, migratory behaviour and the experimental approach used (direct vs. gradual). Our results also showed significant, though sometimes weak relationships between field-reported salinity levels and experimental estimates. Overall, maximum salinities reported for habitats occupied by inland fishes were lower than experimentally-estimated tolerances.Improved understanding of fish salinity tolerance will be essential for assessing impacts of freshwater salinization and forecasting the invasion potential of non-native species.