Abstract

Group living enhances foraging efficiency, yet whether this benefit extends across developmental stages and how social coordination versus emotional buffering contribute remain unresolved. Using zebrafish (larvae 10 dpf, adults 80 dpf) in a Y-maze foraging task with high-resolution tracking and mirror experiments, we show that grouping reduces foraging latency in adults, but not larvae. Adults form coordinated groups (high polarization, small inter-individual distances), whereas larvae form loose aggregations. Adults, but not larvae, exhibit reduced freezing (social buffering) when grouped. Mirror presented visual cues suffice to enhance foraging via emotional calming - reducing freezing and stabilizing speed - yet disrupt real group coordination. Our results reveal a dual mechanism - instrumental coordination and emotional buffering - by which group behavior promotes foraging. Both mechanisms are developmentally gated, emerging only after maturation, offering insights into the ontogeny of social competence and practical implications for aquaculture and conservation.