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A 2 9 3 factorial experiment was designed to study the effect of sublethal toxicity of technical grade copperoxychloride, dietary vitamin E and their interactions on growth performance, some blood parameters, DNA fragmentation and histopathological lesions of Nile tilapia (Oreochromis niloticus). The 96 h LC 50 of copperoxychloride was found to be 129.21 mg/l. Four hundred and fifty fingerlings with an average initial body weight ranged from 1.92 to 2.04 ± 0.11 g were randomly distributed equally in six treatments (T1-T6) with each of triplicates. T4, T5 and T6 were exposed to sublethal concentration 0.25 LC 50 of copperoxychloride. Fish of T1, T2 and T3 fed diet supplemented with different levels of vitamin E (0, 1 and 2 g/kg diet), respectively. While fish of T4, T5 and T6 fed diet supplemented with different levels of vitamin E (0, 1 and 2 g/kg diet), respectively. At the end of the experiment (90 days) the results indicated that fish exposed to 0.25 LC 50 of copperoxychloride and fed diet with normal level of vitamin E, showed significantly lower values (P \ 0.01) of all growth and feed utilization parameters, white blood cells and immunoglobulin M, but they showed significantly increased (P \ 0.05) values of alanine aminotransferase, aspartate aminotransferase, hematocrit, hemoglobin, uric acid and creatinine. Fish fed with varied concentrations of vitamin E neutralized the toxic effect of copperoxychloride as well as vitamin E, significantly lowered the hematological and biochemical response and enhanced the growth parameters and feed utilization. The toxic effect of copperoxychloride exposure and vitamin E feeding on histopathological alterations of liver and gill of the same studied fish will be taken in concern. The results showed improvement in samples treated with vitamin E. This study suggests that vitamin E can be effectively used to decrease the toxic effect of copperoxychloride on O. niloticus and its amelioration through dietary vitamin E supplementation.

River Nile Damietta branch The present study was carried out at El-Kanater El-Khayria & Talkha stations, Damietta branch of the River Nile. The concentrations of heavy metals (iron, zinc, copper, cadmium and manganese) in water and their accumulations in organs (muscles, gills, liver and kidneys) of Oreochromis niloticus fish were determined seasonally during year 2016. Also, the histopathological alterations in the same organs of selected fish samples were studied during the same year. The obtained results showed an increase in heavy metals concentrations in water collected from investigated area and these concentrations followed an abundance of: Fe > Mn > Zn > Cu > Cd. These metals accumulated in some organs of the studied fish and caused histopathological alteration in these studied organs. The histopathological alteration included degeneration, necrosis, edema, hemorrhage, hemolysis, hemosiderin, parasitic forms and hyperplasia in selected organs. Those changes were observed in all studied organs at the two stations during the period of study with severe degree at Talkha station during hot seasons. So, it is necessary to treat the polluted water before its discharging into the Damietta branch to protect fish and human beings from the dangers of pollution.

Keywords:River Nile, Rosetta Branch, water quality, heavy metals, Orechromus niloticus, Inter-simple sequence repeats (ISSR)The present study aims to evaluate the water quality of two locations in Rosetta Branch of River Nile and its histopathological and genetic adverse effects on Nile tilapia (Oreochromis niloticus). Water and fish samples were collected from up and downstream of El-Rahawy Drain discharge point (location I and II, respectively) during the summer and winter seasons. The water quality, liver histopathology and DNA alteration of fish was examined. ISSR-PCR technique was used to assess the genetic variation of fish samples from these locations. The water quality parameters ( BOD, COD,……)were increased at location II compared with location I in addition to depletion in dissolved oxygen. Moreover, the fish samples collected from location II showed severe histological and molecular alterations than those collected from location I. It is recommended that the government must increase the awareness of people around the River Nile, and improve the environmental management to reduce the risks of polluted water and consuming the fish exposed to this water on human health. Hashem et al. , 2020 20Impact of the water quality of River Nile on Oreochromis niloticus _________________________________________________________________________________ 21