Patterns of age and growth of a sedentary damsel fish Acanthochromis polyacanthus were tested over a latitudinal range of approximately 10 degrees (1,200 km) on the Great Barrier Reef, Australia. Within latitudes these patterns were also compared on reefs across a continental shelf that ranged in width from 52 to 128 km. Although variation in length-max, growth, age-max and the von-Bertalanffy metrics of L, and K were found within and among latitudes, greatest variation in some demographic characteristics were found across the shelf regardless of latitude. Fish were always smaller at inner shelf reefs and grew more slowly when compared to mid and outer shelf reefs. The oldest fish collected was 11 years old and, there were no consistent variation in age-max among distances from shore. On outer reefs, there was a linear relationship with age-max and latitude. This ‘tropical gradient’ of age only explained 34% of the variation, further this was not found when the oldest 10% of fish were considered. Fish only reached an age-max of 6 years on the southern-most reefs. There was a trend for a smaller L with latitude but, it was not significant and L did not vary predictably with water temperature. The sampling of MPAs did not confound the resultant patterns. Instantaneous mortality rates were 0.245-0.685, highest at inner reefs and showed no consistent MPA-related patterns. Our study suggested that the mid and outer shelf waters of the GBR appeared best suited for growth of A. polyacanthus. In conclusion, position on continental shelves and related local environmental conditions needs to be considered in spatial models of growth.