Escaping predation is essential for species survival, but prey must effectively match their response to the perceived threat imposed by a predator. Fish evaluate their surroundings using several sensory stimuli, including olfactory, visual, auditory, and mechanical cues. A range of taxa use the fast-start response to evade predators, including fishes, sharks, and larval amphibians. While the fast-start response (rapid bursts of swimming) is extensively studied in solitary fishes, the factors that mediate the collective escape response in schools of fish have historically been investigated far less. To address this knowledge gap, the collective escape behavior and individual escape performance of schools of the tropical damselfish species Chromis viridis, a common gregarious and coral-associated coral reef fish species found throughout the Indo-Pacific, were investigated. The first data chapter explored the theory of optimal group size, comparing various sized groups of fish. Fish strategically adjusted their escape response in coordination with other group mates, validating the connectivity within conspecific schools. The second data chapter investigated how degrading coral health influences antipredator behavior in fish schools. Habitat degradation was revealed to have a negative effect on schooling, and the combination of a chemical alarm cue intensified this impact. While the singular effect of a chemical alarm acted as a prewarning to strengthen the fast-start.