Photobacterium damselae subsp. damselae (PDD) is a pathogenic bacterium with wide distribution, a broad spectrum of host infection, and a high mortality rate in infected animals. Therefore, it is considered one of the most dangerous pathogenic bacterial species in mariculture worldwide. Among the current alternative aquatic disease preventive therapies, phage therapy has attracted widespread attention due to its strong specificity, fast effects, non-toxicity, and lack of pollution. In this study, we identified a bacteriophage that can specifically lyse PDD in the silver pomfret culture environment. The genetic material of the bacteriophages was confirmed to be DNA. Additionally, we studied the effects of bacteriophages under different environmental conditions. Furthermore, we also conducted treatment experiments on silver pomfret using this bacteriophage, and the results showed that the phage had a certain protective effect on silver pomfret infected with PDD. In summary, we isolated and screened a bacteriophage with relatively stable biological properties against PDD, providing a certain theoretical basis for preventive strategies against PDD infection in silver pomfret mariculture.