The purpose of this study was to assess metal concentrations (Al, Cd, Pb, Hg and Ni) in Sabal drainage canal (Al-Menoufiya Province, River Nile Delta, Egypt) water as well as their accumulation in some selected organs (skin, muscles and kidneys) of Oreochromis niloticus fish to evaluate their hazard levels in relation to the maximum residual limits for human consumption. Drainage canal water was found to be heavily polluted with metals which far exceeded the permissible limits. It was found that metals accumulated in organs of O. niloticus in concentrations higher than those of canal water. Kidneys of O. niloticus contained the highest concentrations of the detected metals, while skin appeared to be the least preferred site for the bioaccumulation of metals as the lowest metals concentrations were detected in this tissue. The present study shows that fish organs contained high levels of metals exceeding the permissible limits values. Metals in muscle of fish were higher than the maximum permissible concentrations for human consumption. Thus, consuming fish caught from drainage canals is harmful to the consumers.
This study was carried out to assess the ability of using pawpaw (Carica papaya) seeds as a natural reproduction inhibitor for tilapia fish (Oreochromis niloticus) culture to control its breeding. Biochemical, physiological and histopathological effects ofpawpaw seeds on male tilapia fish were also determined. Mature male tilapia were stocked for 4 weeks and treated with low dose (3 g/kg/day) and high dose (6 g/kg/day) of ground dried pawpaw seeds mixed with their feed. The obtained results showed that the pawpaw seeds induced permanent sterility in the high dose treated fish while the low dose treatment showed reversible results. The results also demonstrated that fish treated with high dose of pawpaw exhibited higher biochemical and physiological effects as: low meat quality, a progressive fall in erythrocyte (RBCs) count, hemoglobin (Hb) content and haematocrit values. Also the high dose revealed a significant increase in the leukocytes (WBCs) count, serum glucose, total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine and uric acid levels. Moreover, serum total lipids revealed a significant decrease compared to control group. On the other hand, the low dose treatment revealed lower biochemical and physiological changes. Histological sections of testis showed disintegration of sperm cells and focal necrosis of seminefrous tubules in the high dose treated fish, hepato-pancreas and posterior kidney tissues also showed severe changes in high dose treated fish. Milder degenerative changes in some necrotic foci and slight changes in hepato-pancreas and posterior kidney were observed in the low dose treated fish. The study concluded that pawpaw seeds which are cheap and easy to obtain, can be incorporated into fish feeds with adjusted amount and be used to control breeding of tilapia fish in growing ponds instead of unfavorable and expensive hormonal use.
The present study evaluated the effects of dietary onion (Allium cepa)powder and its extracts on growth, blood biochemical parameters, non‐specific immune parameters and potential disease resistance against pathogenic Aeromonas hydrophila infection in Oreochromis niloticus. Fish formulated diets containing onion powder (1% or 0.5%) or onion alcoholic extracts (1% or 0.5%). At the end of the experiment, the weight gain and specific growth rate were significantly increased than control. Besides, red blood cells (RBCs) and haemoglobin (Hb) showed a significant increase with insignificant changes of leukocytic cells count (WBCs), triglycerides, creatinine and uric acid levels. Results showed significant increase of total protein and albumin, and significant enhancement of innate immune response including serum globulins, serum antiprotease, lysozyme activities, myeloperoxidase content and the phagocytic index compared with the control group. Meanwhile feeding on onion increased superoxide dismutase, catalase activities and glutathione‐S‐transferase but significantly decreased hepatic peroxidase. The cumulative mortality of O. niloticus injected with A. hydrophila exhibited relatively low mortality levels in all onion supplemented groups. The relative per cent survivals were 100%, 100%, 80% and 70% in 1% onion powder, 0.5% powder, 1% extract and 0.5% extract groups, respectively, compared with control (60%). Additionally, there was a significant increase in relative immune gene expressions of interleukin 1‐beta (IL‐1β), and transforming growth factor‐beta 1 (TGF‐β1) in head kidney tissues of treated groups than the control. These results confirm the anti‐inflammatory and antioxidative activities of dietary onion with its beneficial effects on growth performance and disease resistance against A. hydrophila in O. niloticus.
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