Impact of tilapia-dominance on the growth and production of major carps in minor reservoirs

The present study deals with the effect of dominance of Tilapia on fisheries of minor reservoir. In the present study two reservoirs were selected with almost equal water speared area and analyzed for three years. Julur was selected as experimental reservoir due to the dominance of Tilapia (61.23%), where as Bibinagar (17028’48.6N, 78047’34.7”E) was selected as control reservoir, where Tilapia population was negligible (0.27%). The physico-chemical parameters indicated the mesotrophic nature of water in both the reservoirs. The Ichthyofuna diversity in both reservoirs was almost similar. Five major carp’s fry were stocked with similar quantities in three years in both reservoirs. The production of major carps was significantly (t 22.98, P<0.05) effected in Julur due to the dominance of Tilapia when compared to Bibinagar. Tilapia production was also differed significantly (t 5.73, P<0.05) which was more in Julur. Tilapia was responsible for requirement of more major carp fry for production of 1kg major carps. Tilapia also affected the growth rate of major carps; 1kg of major carps was attained in the early part of the third year in Tilapia dominated reservoir when compared to that of Bibinagar, where major carp attained 1kg in 1year. Tilapia consumed more amount of Zooplankton which effected the significant reduction in the growth and production of major carps. The present study indicated that Tilapia population plays a negative role in the growth and production of desirable fishes.