Comparative Evaluation Of The Performance Of Nile Tilapia (Oreochromis Niloticus) Cultured Under Different Climatic Conditions In Tanzania

EXTENDED ABSTRACT

Growth performance and productivity of Nile tilapia (Oreochromis niloticus) is highly influenced by water quality in the pond. On the other hand, water quality is influenced by the climate and ecological conditions of the place. This study evaluated the growthperformance, survival rate, yield, body length-weight relationship and condition factor of Nile tilapia (Oreochromis niloticus) cultured in two districts; Mbarali and Mufindiof Mbeya and Iringa regions,respectively. Furthermore, plankton biomass yield, species composition and biochemical composition of the algae collected from the ponds located in these two districts were assessed. The two districts experience different ecological conditions withhigh and low temperatures.In each district fish were raised in four earthen ponds,each with an average size of 650 m2 for six months. There were two sites per district and two ponds in each site. All ponds were initially drained, cleaned, dried and refilled with water. The ponds were fertilized seven days prior to stocking using urea and Diammonium phosphate (DAP) at a rate of 3 g/m2 and 2 g/m2 ,respectively.Thereafter, fertilization was done fortnightly throughout the experimental period. Sex reversed Nile tilapia fingerlings with an average body weight of 1.00 g were stocked at a stocking density of 2 fingerlings/m2 . Fish were fed with supplementary diet containing 25% crude protein (CP) at 10% of fish body weight in the first month, followed by 5% for the remaining five months. Feeding was done twice daily, at 10.00 to 10.30 am and at04.00 to 04.30 pm. Body weight, length, width and water quality parameters,namelytemperature, dissolved oxygen, transparency, conductivity, salinity, alkalinity, ammonia, nitrate and phosphorus were measured biweekly. Analysis of variance (ANOVA) was used to test the effect of location on growth performance and water quality parameters. Duncan‟s New Multiple Range test was used to test the significance of the differences between a pair of treatment means.