Stocking Density, Length-Weight Relationship and the Condition of Nile Tilapia in Valley Dam Based Floating Cages in Semi-Arid Karamoja Sub-Region of Uganda

Biological indices; length-weight relationship and fish condition are tools for design of husbandry practices and developing policies for fish farming in natural and artificial water systems. We investigated the effects of fish stocking density treatments; A (100), B (150), C (200) and D (250) fishm-3 on growth and well-being of Nile tilapia, reared in floating cages at Arechek valley dam located in Napak District, Karamoja-Uganda. Length-weight relationship and relative condition factor were computed for each treatment and the resultant outputs compared using univariate ANOVA, and regression analyses. Final fish weights (±Stdev) in different treatments were 311.49±114.6, 204.8±30.5, 138±40.2 and 153.3±68.8g while the mean total lengths were 23.29±2.55 cm, 17.5±5.5, 15.6±15.6 and 19.4±3.02 cm, in A, B, C and D respectively. The length-weight allometry was significantly (P<0.05) different among treatments, (F(5, 1081) = 3.102). Mean relative conditions (Kn) were (±Stdev) 1.08±0.08, 1.91±0.13, 0.79±0.08 and 0.65±0.08 in A, B, C and D respectively, and these were significantly different (P<0.05). Water quality parameters did not influence fish growth and Kn, F(4, 59) = 1.849, P>0.05, R2 = 0.111). The variation in condition was mainly due to stocking density (P<0.05). The most appropriate stocking density of Nile tilapia in valley dam using 35% C. P sinking feed is 100-150 fishm-3 of cage