M^le specimens of Tilapia zillii. Magil cephalus. Liza ramada and Soiea egyptiaca were collected from Ayoub and Shakshouk Stations at the west and middle of Qarun Lake. At the same period, other male specimens of M. cephalus. L. ramada and Solea vulgaris were collected from Bardawil Lake. The histological and biochemical findings can be summarized as follows:Histological examination of gills, liver and kidney of the four studied fish species in both lakes showed variable pathological changes. Bardawil Lake fish showed more damage. The histopatho logical features are discussed,Biochemical significant differences were found between the fishes collected from the two stations of Qarun Lake. T. zillii showed significant higher values of liver total proteins (TP) and inorganic phosphorus (P) than the other three species, while L. ramada showed significant higher values of liver alkaline phosphatase (ALP) and calcium (Ca). Muscle total cholesterol (TCh), low-density lipoprotein (LDL) and Ca were higher in M cepkalus but TP, high-density lipoprotein (HDL) and P in L. ramada; ALP and total lipids (TL) in Solea egyptiaca and triglycerides (TG) in Z zillii,
Mugil cephalus of Bardawil Lake showed significant higher values of muscle TP, ALP, TL, TG, HDL, LDL and Ca than the other two fish species- Muscle TCh and P were significantly higher in 5. vulgaris and L. ramada respectively. Also S. vulgaris showed significant higher values of liver TP and P and L. ramada showed significant higher values of liver ALP and Ca.