Proximate composition of commercially important fish species in southern Gulf of Lake Tana, Ethiopia

Abstract

The aim of the study was to determine the proximate composition of each sex of Oreochromis niloticus, Clarias gariepinus and Labeobarbus intermedius fish species from the southern Gulf of Lake Tana, Ethiopia. The fish samples were collected during the dry season of 2014 from the three fish landing sites, i.e., Bata, Micheal and Giorgis, where local fishermen sell their catches. Species were identified via morphological examination and color. Sexes were identified by observing genital papilla and gonads after dissection. After measuring weight and length of young fish species, fish weighing 201-310 g were selected for the study. A total of 72 fish, eight and four fish per species and sexes were selected, respectively, for each site. The sample size was determined using “resource equation" method. Only edible fillet was labeled and transferred to plastic bags according to species and sex. Then the sample was transported for proximate analysis to Addis Ababa Food Science and Nutrition laboratory using icebox at about 4 °C. Fish sample composites were prepared by taking the fish samples from the three fish landing sites for each sex and species. Samples were thawed at room temperature and oven-dried at 60 °C for 72 h, then ground into a fine powder. Proximate composition was determined following the procedure of Association of Official Analytical Chemists (AOAC). Data analysis was conducted using analysis of variance (ANOVA). Nutrient content significantly varied among fish species; more protein was recorded from O. niloticus and fat from L. intermedius. Also, fat, ash and gross energy content were different between sexes; female fish contained significantly more fat and gross energy than males. In conclusion, consumers are advised to consume these species to obtain required nutrients.