Escape responses in schooling fish have been researched at length, though little is known regarding how responses may differ as schooling fish grow. To investigate this, we elicited escape responses in a subset of individuals from schools (consisting of 20 individuals) of different size ranges of shiner perch (Cymatogaster aggregata), by triggering a visual stimulus when 3-6 individuals were positioned l within view of the stimulus, with their resulting reaction to a threat ensuing further responses across the rest of school which could not see the stimulus because of an opaque barrier that was suspended above the water level. We analysed individual turning rates, latencies, and the propagation of the reaction among individuals. Our experiments revealed distinct patterns in response behaviour: as expected, turning rate decreased with fish size. Conversely, these smaller individuals exhibited longer latencies in initiating the escape response, suggesting a trade-off between speed of turning and reaction time across sizes. Furthermore, size was found to significantly affect the spread of information among individuals that detected the escape-triggering stimulus, with larger individuals facilitating faster propagation of the response throughout the school. These findings highlight the complex interplay between individual size and collective behaviour in fish schools, suggesting that size not only influences individual escape performance but also the efficiency of information transfer within groups. Our results contribute to a deeper understanding of the mechanisms underpinning escape responses in gregarious fishes, with implications for the study of predator-prey interactions and the evolutionary dynamics of schooling behaviour.