Coral reefs are experiencing increased frequency and severity of major disturbances, which contribute to coral loss and reef degradation. Major disturbances to coral assemblages can have important consequences for reef fishes, especially highly specialised species with an obligate reliance on corals. The chevron butterflyfish, Chaetodon trifascialis, is highly territorial, among the most highly specialised corallivorous fish, and while it is shown to be vulnerable to extensive coral depletion, their specific responses are poorly understood. This study tested for variation in territorial behaviour and condition of individuals relative to spatial variation in coral cover across four mid-shelf reefs on the Great Barrier Reef, Australia. Coral cover ranged from 26.5% - 73.4% between sites with the cover of tabulate Acropora between sites being 13.3% - 44.8%. However, variation in overall coral cover had limited effect on territoriality or physiological condition of individuals. While Chaetodon trifascialis is clearly vulnerable to coral loss, our study showed that their behaviour and territoriality is strongly influenced by their unique sociality.