The oceans are warming and acidifying at unprecedented rates. My thesis explores marine fishes’ ability to adapt using anemonefishes and host sea anemones. I found juvenile anemonefish’s vulnerability to acute thermal change increases with mass. End-of-century temperature causes sea anemone bleaching, whereas pH has no measured impact. Early-stage range expansions of anemonefishes are occurring in a climate change hotspot, yet establishment is habitat limited. Finally, anemonefish facilitate sea anemone bleaching recovery, likely due to augmented nutrients. While climate change is causing detrimental impacts, marine fishes and their habitat can display thermal plasticity, resistance, resilience, and adaptation.