This study compared length-weight relationship and condition factor of male Nile tilapia raised in two districts experiencing different climatic conditions in Tanzania, Mbarali and Mufindi. Fish were raised for six (6) months and measurements were done biweekly. The results suggests negative allometric growth pattern (b < 3) for the fish grown in both experimental locations. The “b” values for the lengthweight relationships were 2.87 and 2.94 in Mbarali and Mufindi, respectively. The correlation coefficient and coefficient of determination indicated strong relationship (>99%) between length and weight of the fish. The condition factor (K) ranged from 2.74 to 3.50 in Mbarali and 1.96 to 2.40 in Mufindi, throughout the experimental period. Significantly higher condition factor was observed for fish grown in Mbarali (3.168 ± 0.056) than those in Mufindi (2.166 ± 0.056). It is concluded that, the climate of Mbarali provides better conditions for growth of fish than that of Mufindi.