Saudi Arabia’s extensive coastlines along the Red Sea and Arabian Gulf offer vital marine resources where Lethrinus nebulosus faces threats from parasitic and bacterial coinfections. This study investigates the prevalence and interrelation of the digenean parasite Pseudoplagioporus sp. Yamaguti, 1938 and various pathogenic bacteria, examining their correlations with host morphometric traits (weight, length, width, age, and sex). This research provides novel insights into the synergistic impact of these pathogens on fish health, a neglected area of study in Red Sea fisheries. Over 5 months (September 2022-March 2023), 35 fish were collected from Al-Qunfudhah. A total of 35 samples were initially collected; however, 7 samples were excluded from the study due to severe clinical sickness/poor condition, which made them unsuitable for accurate dissection and parasitological examination. Therefore, a final sub-sample of 28 specimens was successfully dissected and analyzed. successfully examined. Six bacterial genera, including Staphylococcus, Escherichia coli, and Salmonella, were identified alongside internal parasites (n = 16 Digenea). Statistical analysis (ANOVA and t-test) revealed significant inverse correlations (P < 0.05) between bacterial frequency index and host morphometric parameters. Notably, male fish exhibited higher susceptibility to both bacterial and parasitic infections compared to female fish. Furthermore, the interaction between Pseudoplagioporus sp. and pathogenic bacteria appeared competitive rather than symbiotic, suggesting that coinfections significantly alter host immunity and condition factors. These results prompt the development of integrated strategies for monitoring fish health and controlling infectious agents in marine ecosystems.