Rising temperatures, increased marine heatwave frequency and severity, and concomitant water deoxygenation resulting from anthropogenic climate change is increasingly affecting marine organisms worldwide. Tropical coral reef fish are particularly sensitive to these changes as the result of adaptation to the narrow temperature ranges and high oxygen saturation levels typical of coral reef ecosystems. Additionally, successful reproduction forms the basis for ecosystem productivity but is a highly sensitive life stage for reef fishes due to high metabolic demand. Both reproductive and metabolic processes are optimized under certain temperatures and high oxygen levels, thereby providing a mechanistic link between reproductive success and environmental stress. Focusing on a commercially important coral reef fish species, the convict tang (Acanthurus triostegus sandvicensis), this study compares the capacity of reproductive and non-reproductive adults to tolerate the combined effects of acute thermal stress and reduced oxygen availability that occur during marine heatwave events. We expected reproductively active fish to have lower aerobic metabolic scope and hypoxia tolerance than reproductively inactive fish following exposure to simulated marine heatwaves. Preliminary analysis indicated that metabolic rate increased with temperature while hypoxia tolerance decreased. Here we present our results and show how global climate change threatens to alter reproductive processes of reef fishes. As long-term population viability, ecosystem productivity, and the livelihoods of community subsistence fisheries all depend on the reproductive success of reef fishes, this work provides a critical step in clarifying the reproductive consequences of unabated climate change for coral reef fishes.