Abstract:
This study was conducted in the Jebel Aualia Dam, constructed on the White Nile near the capital of Sudan, Khartoum during the period from 1-21 MAY years 2017.The water were taken from Surface water from up and downstream of dam at depth of 10 cm and fish samples were taken from the up and down streams of the dam, 200 meters far from the dam. Use SPSS to analyze data with T independent test and use Excel (windows 2013). The water Samples analyzed to find out for some physiochemical characteristics. Fish caught from up and downstream at the same period and the available fish species in catch were determined and their weights were estimated. The results showed that most of the water properties such as temperature, dissolved oxygen, pH, ammonia and thermal conductivity had some changes in properties. The difference was not statistically significant.The most common fish species foundwere Oreochromisniloticus,Chrysichusysauratus, Murmurs niloticus, Latessniloticus ,Synodontis , Schilbeidae , Labeoniloticus, up and down stream and also the results showed a difference in fish weights between the up and down of the dam, the average weights at the upstream of the dam ranged between 235-400 kg, and the average weights at the down of the dam ranged between 192-281 kg. In addition, there is a difference in the abundance of fish at the up compared to the down of the dam. This difference is attributed to a higher temperature at the down of the dam compared to the up of the dam, a decrease in the level of oxygen, and an increase in the pH, which in turn leads to an increase in the percentage of total ammonia in the water. All these changes in the quality of water are factors affecting the life of fish and thus play a direct role in their abundance.
