Estimated at over 1,600 species, the reef fish community of the Great Barrier Reef Marine Park (GBRMP) is diverse, productive and of immeasurable ecological and human value. The AIMS LTMP has monitored these fish communities for 30 years across the entire latitudinal and cross-shelf span of the GBR, on representative reefs of both fished (blue) and no-take (green) zones. Over this time period, the largest influence on fish assemblages have been disturbance events, while fishing impacts are restricted to a few primary (Plectropomus and Variola spp.) and secondary (e.g. Lutjanus spp. and Lethrinus spp.) target species. These species have benefited from no-take zones in that both their abundance and biomass are higher than in fished zones, with increasing evidence of spill-over into blue zones. Fish species composition varies significantly according to shelf position, with different species representing each functional group across the inshore-offshore gradient. Cross-shelf differences far outweigh latitudinal, and taxonomic shifts over time were never enough to overcome the underlying biogeographic patterns. Inshore reefs have a distinctive and less varied species assemblage than midshelf and offshore reefs, but remain productive, with green zones providing adequate protection to target species and acting as a buffer to disturbances.