Baited remote underwater video stations (BRUVS) were used to examine variation in assemblages of reef fishes at scales of 100s of kilometres (between 3 marine parks in New South Wales, Australia) and kilometres (between 4 sites within each park). Temporal variation over 5 yr was also examined in 1 park (Solitary Islands). BRUVS were able to sample the relative abundance and distribution of species from a wide range of trophic groups, and were particularly effective for detecting cryptic predators. Significant variability in the fish assemblages occurred between each park consistent with the latitudinal distribution of the parks. Fish assemblages also varied significantly between sites within each park. Contrary to expectations, total species richness did not follow the expected latitudinal gradient. However, observed geographical patterns in species richness of certain families such as Labridae (greater richness in the most northern park) and Monacanthidae (greater species richness in southern parks) followed expectations. Abundant schooling species, common to all 3 parks, were important contributors to variation between sites. Temporal variation over 5 yr at 1 park was relatively minor compared to the spatial variation among the 3 parks. This suggests large-scale spatial separation is more important for structuring fish assemblages than time. A network of marine parks will therefore be required to represent variation in reef fish assemblages over this latitudinal scale.