Parasite infections pose a significant threat to the health of fish and the sustainability of fisheries, impacting both the ecological balance and the economic value of marine fish populations. Despite this, comprehensive data on the prevalence of helminths in these hosts, including digenean trematodes, remain scarce in Thailand. Previous studies have focused on only a few species of marine fish and have had limited taxonomic precision in identifying the detected parasites. This study aims to fill this knowledge gap by providing baseline data on the diversity of digeneans across a variety of marine fish species. From July to August 2024, a parasitological survey was conducted in the Gulf of Thailand. More than two hundred marine fish, representing over 50 fish species, were analyzed for the presence of parasites. Each fish was dissected to search for trematodes, and isolated worms were preserved for taxonomic studies. Subsequently, the recovered trematodes were studied in the laboratory using standard parasitological techniques to determine their taxonomic status. The findings revealed that 26.4% of the fish were infected with digenean trematodes. These trematodes belonged to five families: Acanthocolpidae, Allocreadiidae, Bucephalidae, Hemiuridae, and Lepocreadiidae. Several of the reported trematodes are cited for the first time in Thailand. These results offer valuable insights into the presence and taxonomy of digenean trematodes in this understudied region. This study underscores the need for continued research to further understand the helminth communities of marine fishes in the Gulf of Thailand.