Clinostomum spp. are digenetic trematodes characterized by high genetic diversity and complex life cycles involving three hosts: snails, fish, and birds. These parasites signifi-cantly impact freshwater ecosystems, particularly when infecting fish as the second in-termediate host. Despite their ecological importance, no studies have examined the morpho-molecular characteristics of Clinostomum spp. from freshwater fish species in Oman, limiting our understanding of their life cycles and potential threats to the local aquatic environment. The present study investigated Clinostomum spp. infecting killifish (Aphaniops sp.) from four locations in the Muscat region of the Sultanate of Oman (Al Amirat, Al Khoud, Darsait, and Al Bahayes) using integrated morphological and mo-lecular approaches. Metacercariae were morphologically characterized through organ measurements and molecularly identified using mitochondrial cytochrome c oxidase subunit I (COI) sequences. Morphometric analysis revealed that Clinostomum parasites from Omani freshwater bodies were consistently smaller than the established species C. complanatum and C. marginatum reported from other regions. DNA sequence analysis indicated that the Omani specimens were closely related to, but distinct from, Turkish C. complanatum, suggesting they may represent a potentially novel species or subspecies.