This study investigated whether teeth and dorsal fin spines could be used as non‐lethal methods of age estimation for a vulnerable and highly valued tropical fisheries species, coral trout Plectropomus leopardus. Age estimation of individuals from 2 to 9 years old revealed that dorsal spines represent an accurate ageing method (90% agreement with otoliths) that was more precise average per cent error (APE) = 4·1, coefficient of variation (c.v.) = 5·8% than otoliths (APE = 6·2, c.v. = 8·7%). Of the three methods for age estimation (otoliths, dorsal spines and teeth), spines were the most time and cost efficient. An aquarium‐based study also found that removing a dorsal spine or tooth did not affect survivorship or growth of P. leopardus. No annuli were visible in teeth despite taking transverse and longitudinal sections throughout the tooth and trialling several different laboratory methods. Although teeth may not be suitable for estimating age of P. leopardus, dorsal spines appear to be an acceptably accurate, precise and efficient method for non‐lethal ageing of individuals from 2 to 9 years old in this tropical species.