Information on age structure and growth rates is key to the effective management and conservation of fish species. Currently, this information is most commonly obtained by counting the annual rings forming within the otolith and other calcified structures of fish. This method requires lethal sampling which poses ethical and practical challenges for scientific studies of fish populations. The establishment and development of DNA-methylation aging over recent years provide a promising non-lethal alternative. In this study, we used conserved known age-attributed sites from the Zebrafish (Danio rerio) genome to develop an epigenetic clock for Australian bass (Percalates novemaculeata), an ecologically and economically important species native to the coastal drainages of eastern Australia. This was achieved using individuals of a known age and individuals aged using otolith techniques. We found a high correlation in age between the epigenetic and traditionally aged fish (Pearson correlation > 0.96), and a median absolute error of 0.3 years. We also found that the epigenetic aging accuracy was consistent between sex, despite the sexual dimorphism in growth seen in Australian bass. This study further demonstrated the potential of epigenetic aging as a non-lethal aging alternative and as an important tool in the ongoing monitoring and management of wildlife populations.