Modeling Nile Tilapia Heterogeneous Growth under Different Stocking Densities during Pre-Grow-Out Stage

The heterogeneous and homogeneous growth (HmG) assumptions in an intensive tilapia Oreochromis niloticus pre-grow-out production were evaluated under the different stocking scenarios. Four growth models (von Bertalanffy, Logistic, Pütter, and Gompertz) were tested and modified to include the effect of stocking density and growth difference. Models with homogeneous growth were fitted using a nonlinear regression, while heterogeneous growth (HtG) models were parameterized using quantile (0.05, 0.15, 0.25, 0.50, 0.75, 0.85, and 0.95) regression. According to goodness of fit and validation, the models that best fit homogeneous and HtG were Logistic and von Bertalanffy, respectively, which confirm the existence of the dense dependency effect on growth performance. Density and growth have an inversely proportional relationship. Quantile regression provided greater efficiency in predicting growth of the different groups of individuals in the population. The results obtained can be used by the aquaculture farmer to select stocking management strategies and optimal transfer time for tilapia juveniles.