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The current study investigated the bioaccumulation of heavy metals, as well as, physiological and histological alterations, in gonads of Catfish (Clarias gariepinus) inhabiting the polluted location (main basin) and a relatively clean area (southwest basin) at Lake Maryout. A significant (P<0.05) decrease was recorded in muscle total protein and lipid in fish collected from the main basin in comparison to the southwest basin. In contrast, a significant (P<0.05) increase in muscle water content was detected in fish collected from the main basin. A significant (P<0.05) decrease in LH, FSH, estrogen, and progesterone hormones, as well as the activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), were detected in fish collected from the main basin in comparison to the southwest basin. Histological observation of ovary showed lytic ovary with some stages of oocytes include early pre-vitologenic, atretic late pre-vitologenic, wide inter-follicular space and loose tunica albugenia. On the other side, testes pathologies showed completely disorganized lobule structure, accompanied by a reduced number or disappeared of germinal cells, increased interstitial space with reduced interstitial cells. In conclusion, this study confirmed that the main basin of Lake Maryout suffered from great pollution that affected completely on the fish population and the situation needs the rapid intervention of the Egyptian government to stop agricultural, industrial and health drainage in Lake Maryout by establishing treatment units before direct drainage in the Lake

This study was carried out to assess the accumulation and distribution of heavy metals (Pb, Hg, Cd, and As) in Lake Maryout. The impact of heavy metal contaminations was also assessed in different target tissues (gills, liver, kidney, and muscles) of Clarias gariepinus (C. gariepinus) using physiological and histopathological parameters in the Main Basin and a relatively clean area (South-west Basin). Heavy metals concentration in water showed that Main Basin had the highest levels of Pb, Hg, As and Cd metals. The abundance of heavy metals in different fish organs; gills, livers, kidney, and muscles followed the order: Pb> Cd >As >Hg. Fish muscle compared to other tissues; usually, contain the lowest level of metals. Physiological alterations showed a significant severe anaemia, leukocytosis, neutrophilia, lymphopenia, and monocytosis was detected in fish collected from Main Basin in comparison to South-west Basin. Moreover, a significant increase in serum ALT, AST and creatinine were observed, while serum urea showed insignificant decreased in fish collected from Main Basin in comparison to South-west Basin. Histopathological alterations of gills showed lamellar fusion and hypertrophy of epithelial cells. Liver samples included necrosis of hepatocytes. Finally, kidney pathologies demonstrated the glomeruli appeared shrunken, desquamated, and vacuolated and often destroyed tubular epithelium. The mean fish intake of adults provides exposure to metals that fall within the accepted standards for the safe intake. It is recommended that the situation need a scientific method of detoxification to improve the health of this Lake and economic fish.

The present investigation was designed to evaluate the dangerous effects of the Pb and Hg on Clarias gariepinus inhabiting Lake Mariout and assay the possible protective effect of meso-2, 3 dimercaptosuccinic acid (DMSA). The test fish were divided into four groups kept in plastic tanks (20 fish each) containing 30L of Lake Mariout water. Group (1): Standard group (zero time); Group (2): Unexposed DMSA group, Group (3): Low dose DMSA group; Group (4): High dose DMSA group. Fish exposed to DMSA showed significant decrease in lead (P≤0.05) and mercury concentrations (P≤0.05) in kidney, liver, gills, muscle and blood than unexposed group. The present results clearly indicate a significant decrease in RBCs, Hb, Hct, and platelet counts while a significant increase in MCH, MCHC, and WBCs in the Clarias gariepinus collected from the main basin of Lake Mariout. A marked significant decrease in AST, ALT, urea, creatinine (P≤0.05) was observed in DMSA groups. A significant increase in CAT, GPX and SOD was observed after exposure to DMSA. In addition, DMSA exposure improved the histopathological alterations in fish liver and kidney.