Pêche et production animale

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Analysis of Diet and Biochemical Composition of Nile Tilapia (O. niloticus) from Tekeze Reservoir and Lake Hashenge, Ethiopia

Tsegay T, Natarajan P and Zelealem T

A study was conducted to investigate the biochemical composition and diet type of Nile tilapia (Oreochromis niloticus) collected from Tekeze reservoir and Lake Hashenge, Ethiopia between December, 2014 and March, 2015. A total 100 fishes were collected from the two water bodies 50 from each by gill nets of 10, 12 and 14 cm stretched mesh size. The stomach contents were analyzed using frequency of occurrence and numerical methods. The food items in the stomach covered a wide variety, ranging from various types of phytoplankton to zooplankton and macrophytes. The food composition of O. niloticus showed that, there was variation within the fish species across the study areas. The major food items in terms of frequency of occurrence collected from the stomach of O. niloticus in Tekeze reservoir were Pediastrum (68.85%), Microcystis (60.45%), Peridinium (59.70%) and Staurastrum (41.56%) and from Lake Hashenge were Daphnia (63.12%), Copepods spp (56.90%), Nauplii (52.11%), and Macrophytes (45.56%).The contribution of zooplankton (Daphnia, copepods and Nauplii) was higher in case of Lake Hashenge but Pediastrum spp., Microcysts spp. and Peridinium spp. which were phytoplankton type were the dominant food items of the fish in Tekeze Reservoir. The fish species from the water bodies were transported to the laboratory for the estimation of biochemical composition such as crude protein, crude fat, moisture, ash, carbohydrate and some minerals. The chemical analysis revealed that the crude protein content of the fish species collected from the two water bodies were ranged from 15.31-16.32% of wet weight. The crude fat content and ash ranged between 1.20 and 2.45, 0.81 and 1.16% of the wet weight, correspondingly. The concentrations of some elements were significantly different (P<0.05) between sexes and location were the fish was collected. The analyzed mineral content in each species was in the order K>Na>Ca>Mg>P>Fe>Zn>Cu>Mn. This investigation is an important measure towards the data needed to create information of the relationship between food type and biochemical composition. As the present study revealed that the fish species are good sources proteins and fats, there is need to investigate in detail the types of amino acids and fatty acids of the sampled fishes.