Role of some stressful ecological factors on cultured Nile tilapia in relation to metacercarial affections.

This study was carried out to investigate role of some stressful ecological factors on cultured tilapia species, 86 Tilapia zillii and 118 Sarotherodon galilaeus in relation to metacercarial affections. Physicochemical parameters of water samples were within normal level that can tilapia survive and adapte.There were no pathognomonic signs in infected tilapia species. Encysted metacercariae were identified as Diplostomum tilapiae, ,Centrocestus formosanus and Heterophyes sp.The whole prevalence was 28.8 % and the seasonal prevalence were recorded .We evaluated the activity of enzymes (Superoxide dismutase,Catalase,Glutathion peroxidase, Glutathion reductase,Malondialdehyde, Cytochrome oxidase and Lactate dehydrogenase) in gills,liver and musculature of both infected tilapias throughout the different seasons and the statistical analysis were done.