The aim of this study was to investigate the prevalence of infestation and seasonal and age susceptibility of Nile tilapia, Oreochromis niloticus to Enterogyrus cichlidarum over a calendar year. Two weight groups of 100-150g and 150-200g were investigated over the four seasons. Results showed that the average prevalence of E. cichlidarum over a calendar year was 20.56% for the lighter-weight (younger) group, but was 26.11% for the second (older) group. The highest prevalence was during the spring season. The older fish showed higher prevalence and intensity of infestations all over the four seasons. Surprisingly, the fish gastric submucosa showed encysted metacercaria of digenean trematodes (13.61%). The highest prevalence was during the winter season with the average prevalence all over the year of 11.67% and 15.56% for the younger and older groups, respectively. Histopathological studies revealed mild alteration at the site of attachment of E. cichlidarum to the gastric mucosa and a local chronic inflammatory reaction around the encysted digenea within the submucosa.