In the present study, three kinds of fishes , namely 135 Tilapia spp., 133 Mugil capita and 136 Clarias lazera were collected from lake Manzala and investigated to the parasitic infestation allover the year. The seasonal prevalence of general parasitic infestation was high during autumn (48.9 %), while the lowest infestation rate was during spring (32.9 %). Monogenetic trematodes represented the highest infestation rate in autumn (34.3 %), while it was only 17.86% in summer. The crus­tacean parasites were detected allover the year except in spring season. On the other hand nematodes and cestodes were detected allover the yea, while, Acanthocephala were recorded only in summer (4.5 %). The postmortem lesions of the infested fishes revealed congested, hyperem­ic gills with excessive mucus secretions in monogenetic worm infesta­tion. In Crustacean infestation, the destruction of gill lamellae was com­mon. The infestation of the intestine with internal parasites resulted in congestion of intestinal mucosa with excessive mucus secretion. The morpho-pathological microscopic examination revealed severe pathologi­cal tissue alterations in different fish tissues especially at the sites of parasitic attachment.