This study was conducted to investigate the effect of linear and non-linear methods of estimating fish mortality on feed conversion ratio (FCR) and profitability of cage cultured Oreochromis shiranus (Makumba). Two treatments were used, designated as T 1 and T 2 and were replicated three times. In each cage, 105000 fish were stocked at an initial average body weight of 1.59±0.04g and cultured for 365 days. The fish was fed twice a day with formulated feed (36% Crude Protein) at 4-1% body weight

more »

... with feed adjustments based on standing biomass from linear and non-linear estimated mortality. The results showed that there were significant differences between the two treatments on FCR . Final mean weight was 179.41±7.71g and feed conversion ratio was 1.64±0.15 for T 1 and 177.56±8.27g and 1.54±0.14 respectively for T 2 . Profitability of the two treatments was calculated by enterprise budgeting. There were significant effects on gross margin between the two treatments Gross margin values were K302,523,924.30 for T 1 and K356,065,320.29 for T 2 . The study concludes that use of non-linear method of estimating fish mortality affect feed conversion ratio and economic profitability of Oreochromis shiranus cultured in cages. It is therefore recommended to use non-linear method of estimating fish mortality if farmers are to reduce FCR and maximize profits from the cage culture of Oreochromis shiranus as feed wastage due to feed overestimation resulting from miscalculation of mortality, can be minimized by 15.77%.