Some fish grow faster than their conspecifics, even when their life stage, habitat, and feeding conditions are identical. This study investigated potential causes of that inter-individual variability in growth performance for Galaxias maculatus, a diadromous fish species prolific throughout the southern hemisphere. We elastomer tagged 35 wild-caught, similarly sized fish for individual-level identification, and collected mass and length measurements for each fish every 8-10 weeks to track their growth performance over time. After reviewing the first growth performance measurements, we isolated the initially fastest (n=5) and slowest (n=5) growing individuals to see whether social dynamics in the original tanks played a role in determining the growth performance of these individuals. Specifically, we looked for signs of catch-up or compensatory growth in the slow-growing fish, and the emergence of new winners and losers among the fast-growers. Meanwhile, we measured the maximum and standard metabolic rates of each fish in an 18-hour respirometry trial to see if growth could be explained by metabolic traits. Finally, we recorded videos of each tank at feeding time to watch for signs of dominant or aggressive behavior. Analyses are ongoing, but suggest that fast-growing fish are not more outwardly aggressive than slow-growers, and there is no clear metabolic signature to explain growth profiles. As aquatic habitats change, so too will the phenotypes favored in those habitats. Populations with high intraspecific variability in growth performance may be better suited genetically to respond to changing environments, including those associated with climate change. The results of this study give insights into both the present and future growth performance of an ecologically and economically important aquatic ectotherm.