Positive species-species interactions are key relationships in many ecosystems, particularly coral reefs, where many species depend on live corals for shelter and protection from predators. However, these critical relationships are threatened globally by habitat loss, specifically loss of branching coral to myriad global environmental challenges. These losses may affect the antipredator behavior of fishes that depend on live coral, extending sheltering time when they are not feeding and putting them at risk as well. Our objective was to determine if the traits of coral hosts and the surrounding habitat affects the antipredator behavior of Chromis viridis, a site-attached coral mutualist. To quantify perceived fear of fish shoals associated with branching corals, we performed replicate trials measuring flight initiation distance and time to re-emerge from shelter for C. viridis on fringing reefs of Moorea, French Polynesia. We found that the perceived threat to shoals of C. viridis was reduced with larger host corals and increased with distance to the nearest branching coral or other hard substrate. Further, in areas with more complex and continuous reefs, we found C. viridis had a lower perceived risk measured as decreased flight initiation distance. Increased perception of threat also lengthened the time to reemerge, extending the time in the coral when they do not feed. As their habitat is fragmented due to anthropogenic stressors, their antipredator behaviors shift to allocate more energy to sheltering from predators instead of feeding in the water column

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