BIOCHEMICAL EVALUATION FOR THREE FISH TYPES COLLECTED FROM DIFFERENT WATER SOURCES IN EGYPT

Abstract

Currently, the aquatic ecosystem of Egypt is faced with acute environmental problems due to heavy metals pollution; therefore, it is very important to determine the cause for accumulation of heavy metals in water and fish tissues. The aim of this study was to determine the levels of selected heavy metals in water and fish samples collected from different water sources in Egypt and evaluate the proximate composition for these fishes. Water samples and fillet fish species [Nile tilapia (Oreochromis niloticus L.), catfish (Clarias garipinus L.) and common carp (Cyprinus carpio L.)] collected from different water sources in Egypt (River Nile, Lakes and farmed fish) were analyzed quantitatively for the presence of cadmium (Cd), arsenic (As), lead (Pb) and mercury (Hg) using Atomic Absorption Spectrophotometer. The concentrations of 4 elements in water samples (ppb) were: Cd (5 – 84); As (3.14 – 16.14); Pb (1 – 20) and Hg (0.0037 – 0.0105), while concentration of Cd, As, Pb and Hg (µg element/Kg dry mass) in different fillet fishes were ranged between (ND – 79); (ND – 5.528); (ND – 16) and (0.175 – 0.539) respectively. Proximate composition of Nile tilapia, catfish and common carp were (75.2 – 76.8%; 74.3 – 74.6% and 66.9 – 71.8%) moisture, (76.9 – 77.52%; 68.83 – 68.94% and 68.7 – 71.72%) total protein, (18.08 – 18.8%; 25.8 – 26.99% and 23.58 – 26.78%) crude lipids and (4.1 – 4.4%; 4.18 – 5.3% and 4.25 – 4.52%) ash, respectively. The results indicate that Nile tilapia, catfish and common carp have a high nutritional values and the Cd, As, Pb and Hg concentrations in all fish tissues were less than the permissible limits recommended by E.O.S.Q.C. (1993)