Proximate composition of minerals and heavy metals contents of four commercial fresh water fishes of the Blue Nile

Abstract

The fish species from Al-Mowrada fish market were purchased and transported to the Laboratory, Faculty of Science and Technology, Chemistry Department for the estimation of biochemical composition such as crude protein, crude fat, moisture, ash, carbohydrate and some heavy metals. Fresh water species (Auchenoglaris   biscutatus,.  Hydrocynus  forskali,  Labeo   niloticus, and  Oreochromis  niloticus) were collected for this study. Biochemical changes in total protein, carbohydrate, lipid, moisture and ash content were estimated by the standard procedures. This investigation aimed to estimate the toxic impact of selected heavy metals such as Pb, Cd, Fe, Cr and Zn on the biochemical changes in certain freshwater fish, A. biscutatus, H. forskali, L. niloticus and O. niloticus . The measurement of heavy metals like, Pb, Cd, Fe, Cr and Zn were done by absorption spectrophotometry. The total protein content of these species was in the order of 21.36%, 22.19%, 22.60% and 22.46% respectively. The crude fat content and ash ranged between 2.69% and 5.40%, 82.11% and 84.85% of the wet weight, correspondingly. The carbohydrate ranged between 83.49% and 89.94%. The moisture ranged between 73.52% and 81.04%.The highest value of (Pb) was in A. biscutatus and the least was in O. niloticus. The highest value of (Cd) was in A. biscutatus and the least was in L. niloticus. The highest value of (Fe) was in A. biscutatus and the least was in H. forskali. For (Zn) the highest value was L. niloticus and the least was in A. biscutatus. For (Cr) it is only detected in two species which were L. niloticus and in O. niloticus. The amount of (K) contents for the different species was higher than other minerals, while (Ca) was the lowest in most species.