Anomalous warming events, including Marine heatwaves (MHWs), are increasing in frequency and severity globally, due to unprecedented anthropogenic climate change. Since most marine species are ectotherms small changes in their external temperature can have impacts on their physiology, food availability, growth and reproduction. Tropical marine species are particularly vulnerable to thermal environmental changes caused by MHWs as they have evolved in more thermally stable conditions. Past research on tropical fish has shown that acclimation to warming can occur within and across generations, however, there is still a limited understanding how exposure to heatwaves in previous generations may shift thermal performance of future generations. Here, the model coral reef damselfish, Acanthochromis polycanthus, was used to better understand how parental exposure to MHWs might shift thermal limits. Using a unique multigenerational experiment, the ecologically relevant thermal limits were explored depending on whether parent fish experience Control, MHW or Chronic warming conditions. Instead of classic critical thermal limit trials, which likely overestimate the maximum temperatures an individual can survive in nature, this experiment will use a novel temperature-controlled ramp and hold experiment to either 33°C or 34°C, alongside a control group. Fish from the 3 parental treatments and 3 thermal-ramp testing temperatures we sampled from at 0, 6, 12 to 24 hours following the thermal ramp to explore thermal stress via oxidative stress. Three antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) will be quantified alongside the cellular damage indicator lipid peroxidation (LPO) and will be assessed in the liver and muscle tissues. The findings of this study will provide valuable information on multi-generational and developmental plasticity of thermal limits and help conservation and management of coral reef fish in the future.