Assessment of production and profitability of stocking sizes and densities of Nile tilapia for small – scale pond farming

Abstract

The study evaluated growth performance and profitability of culturing monosex male tilapia at different stocking densities and sizes. Two stocking sizes (2 g, 10 g) and densities (3 fish/m², 6 fish/m²) were respectively evaluated from January to August 2020, at Aquaculture Research and Development Center of CSIR-Water Research Institute, Akosombo. The two factorial designs have four treatments (T) as follows: 2 g at 3/m² (T₁), 2 g at 6/m² (T₂), 10 g at 3/m² (T₃) and 10 g at 6/m² (T₄). Average initial weight stocked in four ponds of 200 m² were 2.9 ± 0.6 g, 2.9 ± 0.6 g, 10.2 ± 2.1 g and 10.2 ± 1.7 g. All the experiments were replicated. Selected water quality parameters and experimental fish were monitored at 14 days interval. Based on calculated F-values of fixed effects for growth parameters monitored, both stocking size and density independently had significant impact on final weight, condition factor, weight gain, specific growth rate and fish survival at different probability levels. Final mean weights of fish among the treatments were significantly different (P < 0.05) except for T₂ and T₄. Highest to least final mean weights were 195.0 ± 18.5 g, 181.7 ± 16.3 g, 153.3 ± 27.5 g and 152.2 ± 18.8 g, respectively ranked by T₃, >T₁, >T₄, >T₂. Survival of fish was relatively higher (P < 0.05) for both high stocking size of 10 g (87.5 %) and lower stocking density of 3 fish/m² (90.0 %). Temperature, pH and alkalinity were all within optimal range required by tilapia for growth except DO, NH₃-N and Turbidity which were below the optimal range. T₂ recorded highest return to variable cost of 50.05 % with T₄ been least (9.46 %). Results suggest that higher yield and profitability are achievable for small–scale Nile tilapia pond production at stocking size of 10 g with density of 3 fish/m² density.