Understanding the ecological role and associated behaviours of aquatic animals is often difficult because sampling techniques have inherent limitations. The goal of this study was to explore how different sampling approaches (passive acoustic telemetry and dietary proxies) can be used in conjunction to provide a more refined account of fish behaviour. Fifty-eight acoustic receivers were deployed at three reefs to monitor the movements of an economically significant species group – coral trout (Plectropomus spp.; n≈150 individuals). Additionally, gut content identification (visual - n≈200 and genetic - n≈100) and stable isotope analysis (n≈120 x three tissues) were completed over a two-year period to assess species-specific differences in feeding ecology. By using multiple approaches, we found that broad resource and habitat selection trends differ between sympatric species, but interestingly, the way they differ is unique to each species pairing. For example, at offshore reefs the space use of P. laevis overlapped with P. leopardus, and they consumed distinct prey; while at inshore reefs, the space use of P. maculatus had little overlap with P. leopardus, and they consumed similar prey. These findings demonstrate the value of using complimentary sampling approaches to explore fish behaviour.