Background. Fish farming has been developed due to decline of traditional fishing where tilapia culture is one of the principal sources for fish production. This study was aimed to investigate the prevalence and impact of helminth infection on the health of cultured hybrid tilapia, Oreochromis sp.Materials and methods. Prevalence and intensity of helminth infection and histopathological response of infected organs were studied. Changes of biochemical composition, and protein electrophoritic pattern, and heavy metals levels of liver and muscle tissues were determined.Results. Helminth infection was restricted to the liver of 60% of the examined fish. Of this number 33% were infected by undifferentiated nematode larvae and heterophyid metacercariae while 67% showed the metacercarial infection only. Infection caused a noticeable alternation in histological architecture of the liver that was accompanied by depletion in hepatic glycogen, total lipids, and total protein. Moreover, biochemical components of the muscle tissues were significantly decreased along with intensity of infection. Protein fractions of the liver and muscle tissues were highly variable. Intensity of the parasitic infection was directly correlated with Fe and Mn levels in both liver and muscle.Conclusion. s. Cultured fish also suffered from helminth infection that significantly impaired the health and condition of fish as shown by histopathological, biochemical, and protein fractions changes recorded in this study. In additions, intensity of helminth infection might increase the capacity of infected organs in accumulation of heavy metals.

fish farm, hybrid tilapia, helminthes, histopathology, biochemistry, heavy metals