Abstract <p>For social animals, conspecifics within a group can influence an individual’s physiology and behavior, but whether these group effects alter the trade-offs between foraging and defense remains unclear. In this study, we investigated a social fish species, the juvenile qingbo (<i>Spinibarbus sinensis</i>), to examine how group effects during both past social experiences (rearing conditions) and current social conditions (test environments) influence routine metabolic rate (RMR), behavioral traits (activity, boldness, and sociability), and preferences for food versus shelter, and how rearing conditions (isolation or group rearing) specifically affect growth. Our results revealed that the qingbo reared in social isolation exhibited both higher growth and RMR than did the individuals reared in groups, potentially through compensatory feeding. Group effects from conspecifics during rearing and testing led to increased activity and decreased sociability in the qingbo, whereas the presence of conspecifics during testing increased boldness. Isolation-reared qingbo showed a preference for shelter over both an open field and food in the absence of conspecifics, whereas group-reared qingbo preferred food over shelter when conspecifics were present. These findings suggest that visual social isolation may not be a significant stressor for qingbo, as the isolation-reared qingbo exhibited improved growth. This could be because the presence of conspecific olfactory cues in the rearing environment mitigated the stress associated with visual isolation. Interactions with conspecifics and the associated reduction in predation risk with group effects may enhance activity and boldness. Additionally, the qingbo’s food and shelter preferences can dynamically adjust in response to group effects, reflecting high behavioral plasticity that allows social fishes to optimize foraging efficiency in risky situations.</p> Significance Statement <p>Living in groups can reduce predation risk to animals but also increases intraspecific food competition. Therefore, for social animals, the presence or absence of conspecifics can influence their physiology, behavior, foraging habits and defending strategies. In the social fish species, the qingbo (<i>Spinibarbus sinensis</i>), we found that individuals reared alone exhibited higher growth than those reared in groups. This might be due to group-living individuals spending less time foraging because of collective activities. When conspecifics are present, qingbo become more active and prone to risky behaviors, possibly due to the perceived reduction of threats, such as predation, in group settings. Additionally, we found that the presence of conspecifics and the availability of hiding places in the environment reduced the predation risk for qingbo, leading them to focus less on avoiding risk and more on foraging. Overall, our findings highlight the complex trade-offs in social living, where the presence of conspecifics can influence the foraging and risk-avoidance strategies of qingbo.</p>