The partitioning of beta (β) diversity according to spatial and environmental variables is a tool to elucidate the processes involved in the assembly of ecological communities. We compared the relative effects of spatial and environmental variables on the assembly of west Australian marine fish communities along a temperate – tropical gradient. Null models were used to account for the effect of species pools on β diversity of marine fish from three bioregions, An hierarchical variation partitioning approach was applied to test for the effects of scale and spatial and environmental variables on the β diversity of fish assemblages. Results were compared among bioregions to identify latitudinal changes in the relative importance of processes operating in the assembly of marine fish communities. After accounting for the effects of alpha (α) diversity, small differences were found in β deviations among sampled locations, with β deviation values typically positive, although not large. Fine scale variables explained more β diversity variation than coarse scale variables. Spatial variables explained greater variability in β diversity in tropical locations, and environmental variables explained greater β diversity variation in temperate locations. Our results find support for stochastic assembly of marine fish communities regardless of bioregion. The strong effect of stochasticity in structuring the communities is suggested by small β deviation values and low variability explained by independent variables. Superimposed upon the stochastic nature of marine fish community assembly, a change in importance from dispersal limitation to deterministic processes was found from tropical to temperate environments.