|The mutualism between anemonefishes and giant sea anemones is one of the most well known interactions on coral reefs. While the symbiotic benefits provided to each partner have been researched for over 100 years, little is known about the mutualism at night. Further, the ecophysiological mechanisms that underpin the ecological benefits of the mutualism remain greatly unexplored. Here, I conducted foundational research on the metabolic and behavioral interactions of the anemonefish-sea anemone mutualism at night. Physical contact between anemonefish and sea anemones elevates the net dark oxygen (O2) consumption of the partners. Further, anemonefish engage in more flow modulating activities when sea anemones are present than when anemonefish are alone. Lastly, sea anemone O2 consumption increases with water flow. I conclude that anemonefish behavior at night modulates sea anemone O2 consumption by forced convection of ambient water flow.