RESUMEN
Clinostomatid species metacercariae are commonly found in Tilapia species. Three species of the family Clinostomatidae were observed where Clinostomum complanatum, Clinostomum phalacrocoracis and, Euclinostomum ardeolae were studied at the ultrastructural level using the scanning electron microscope. These parasites were collected from the pharyngeal region, body muscles and kidneys of Tilapia nilotica fish obtained from fish dealers. The shape of metacercariae, sensory papillae found on their surfaces, and the shape of their suckers and excretory pores showed marked difference between the three species. The present work provided some important morphological information's for comparison between three metacercariae of the family Clinostomatidae by the use of scanning electron microscope [SEM]. It also explained the mechanism of attachment of clinostomum complanatum to the host tissues and suggested that the genus Euclinostomum may have the same methods of absorption of glucose as the genus Clinostomum