We investigated the post-settlement survivorship of vagrant tropical fish in temperate marine environments. The arrival of cohorts in Sydney during summer and autumn provides a unique opportunity to understand the factors that contribute to their survival after settling. A large cohort of newly settled Sergeant Major Damselfish (Abudefduf vaigiensis) was sampled in March and April 2021 at Little Manly (Sydney). Otolith microstructure was used to test whether 1) faster-growing settlers had a higher rate of subsequent survivorship; 2) Large size-at-hatch provided any advantage in post-settlement survivorship; and 3) Fish feeding at a higher trophic level were the fastest growing individuals (using stable isotope analysis). The results of the study showed that large size-at-hatch was a significant characteristic in surviving fish, whilst high growth rates and trophic levels were not. After eliminating trophic and growth mechanisms to survivance, video footage taken at the beginning and end of the study period was analysed, suggesting that intra-species competition and dynamics may play a role in the survivorship of tropical vagrant fish in temperate environments.