Many coral reef fishes live in cooperative groups due to the benefits that sociabillity can confer, such as reduced energetic requirements to fuel a variety of basic processes. Most studies on this topic have focused on the reduced costs of locomotion in collectively moving fish, in which trailing individuals can take advantage of the vortices produced by leading fish to maintain swimming speed with reduced effort. Theory suggests that individuals in social groups may also be able to reduce their energy spent on vigilance, as fish groups exhibit improved threat detection by having “many eyes” to scan for predators. In addition, individuals accustomed to a social environment may exhibit reduced stress levels when exposed to shoaling conditions. How these effects may influence overall metabolic demand, however, remain poorly understood. In this study, we quantified the impacts of shoaling on the metabolism and body condition of a gregarious coral reef fish species, the shoaling damselfish Chromis viridis. Using a novel respirometry method, we found that the presence of shoal-mate cues led to a significant reduction in the standard metabolic rate (SMR) of individuals. Although all fish were fed a body-mass specific feeding regime, fish held in isolation exhibited a significant reduction in body condition following one week in treatment when compared to those held in shoals. As environmental disturbances like tropical cyclones have the potential to induce social isolation, these results could have ecological consequences for gregarious fishes on coral reefs.