Abstract:
The rapid expansion of tilapia aquaculture necessitates feeding strategies that enhance growth while minimizing
environmental impacts. This study investigated the effects of three feeding rations 3%, 8%, and 12% of body
weight per day on growth performance, feed utilization, survival, and water quality in Genetically Improved
Farmed Tilapia (GIFT) fingerlings cultured in northern Sri Lanka. A total of 3000 fingerlings (initial mean
weight: 30.62 ± 0.23 g) were randomly allocated into 12 cement tanks (37 m²; stocking density: 250 fish/tank) in a
completely randomized design with four replicates per treatment. Fish were fed a commercial diet (30% crude
protein) thrice daily over 56 days. Weekly measurements included growth parameters, feed conversion ratio
(FCR), survival, and key water quality indicators. Significant differences (p <0.05) were observed in growth and
FCR across treatments. The 8% ration produced the highest performance, with a final mean weight of 338.07 ±
12.4 g and length of 28.01 ± 0.8 cm, outperforming both the 3% (146.60 ± 8.2 g; 16.38 ± 0.5 cm) and 12% (332.27 ±
10.6 g; 27.85 ± 0.7 cm) rations. While the 3% ration had the best FCR (0.25 ± 0.02), its low growth made it
economically unviable. The 8% ration achieved a balanced outcome (FCR: 0.43 ± 0.03). Survival rates were high
(92–96%) with no significant variation among treatments. Water quality remained within acceptable limits,
although higher rations elevated total ammonia nitrogen and total dissolved solids significantly (p <0.01). Overall,
feeding GIFT fingerlings at 8% body weight/day offers optimal growth and efficiency without compromising
water quality or survival. These findings support sustainable intensification of tilapia culture, particularly in
resource-limited tropical regions. Further research should assess economic feasibility in larger-scale production
systems.
