Chemical compositions and heavy metal contents of Oreochromis niloticus from the main irrigated canals (rayahs) of Nile Delta

The present study aimed to assess the seasonal variations of the proximate chemical composition, physicochemical, microbiological aspects and heavy metal concentrations of Oreochromis niloticus muscles collected from The Nile rayahs from spring 2014 to winter 2015. Rayahs are the main irrigated canals of Nile Delta, Egypt and represent El Tawfiki, El Menoufy, El Behery, and El Nasery rayahs. Results showed a spatial and temporal significant difference (p < 0.01) in the proximate composition and Physicochemical aspects of O. niloticus muscles. The moisture, protein, fat, ash, carbohydrates and calorific values varied between (78.55–80.77%), (16.10–17.88%), (1.10–1.95%), (0.55–1.50%), (0.10–0.94%) and (78.37–89.73%), respectively. Heavy metal accumulation in the O. niloticus muscles showed irregular distributions with descending order of: Fe > Zn > Mn > Cu > Pb > Cd. Generally, heavy metals, TVB-N, TMA, TBA and TVC did not exceed the maximum permissible limits in the tissues of O. niloticus. The values of Hazard Index (HI) and Hazard Quotient (HQ) are lower than the acceptable limits, which indicate that the metals in O. niloticus in the Nile rayahs, Egypt, do not pose any particular human health risk concern. Therefore, O. niloticus muscles collected from four rayahs are safe for human consumption and could be used as a source of healthy diet for humans.