Proximate Composition and Fatty Acid Content of Commercially Important Fish Species from Ethiopian Lakes: A Review

Abstract

Fish is an important source of long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) and also a good source of protein. Ethiopian lakes harbor a rich fish biodiversity which vary in their nutrient composition. This review will examine published data on the proximate and fatty acid content of six fish species from various Ethiopian Lakes. The fish species include the Nile tilapia (Oreochromis niloticus) , African sharp tooth catfish (Clarias gariepinus) , Nile perch (Lates niloticus) , Barbs (Barbus sp.) , Redbelly tilapia (Tilapia zillii) and Common carp (Cyprinus carpio) . Species were selected based on their current commercial importance as well as their potential for nutrition. The content of protein, fat, moisture and ash ranged from 13.30 to 18.50%, 0.40 to 2.45%, 77.24 to 80.80% and 0.81 to 1.20%, respectively. The fatty acid content of the fish ranged from 6.42 to 25.01 mg.g -1 dry weight (DW) for saturated fatty acids (SFA), 2.02 to 24.62 mg.g -1 DW for monounsaturated fatty acids (MUFA) and 7.88 to 24.12 mg.g -1 DW for PUFA. Among the SFA, palmitic acid was the main fatty acid while oleic acid and docosahexaenoic acid (DHA) were the main MUFA and PUFA respectively. The highest content of eicosapentaenoic acid (4.74 mg.g -1 DW) was found in Barbs from Lake Langeno while the highest docosapentaenoic acid (3.99 mg.g -1 DW), DHA (11.53 mg.g -1 DW) and total n-3 PUFA (20.61 mg.g -1 DW) were found in Nile tilapia from Lake Haiq. The n-3/n-6 ratios ranged from 1.39 to 5.86 mg.g -1 DW, with the highest ratio coming from Nile tilapia collected from Lake Haiq and the lowest from Redbelly tilapia from Lake Ziway. In conclusion, all the species collected from different Lakes of Ethiopia may be beneficial to human health. However, Nile tilapia from Lake Haiq and Barbs from Lake Langeno are the best for consumption due to higher levels of LC n-3 PUFA.