Determination and application of optimal combination of egg density and water flow rate in tilapia commercial incubation

The central composite design and response surface method were utilized to examine the combined effects of water flow rate and egg density on the commercial incubation of Nile tilapia in the study, aiming at establishing reliable model of the incubation percentage regarding the two factors and ascertaining the optimal factorial combination via model optimization. Results showed that both water flow rate and egg density had highly significant influences on the incubation percentage (P < 0.01); the interaction between two factors on the incubation percentage was found highly significant (P < 0.01), meaning that the influence of one factor on the commercial incubation hinged upon another factor; due to the presence of interactive and quadratic effects, two factors affected the incubation in a curvilinear fashion; the effect of water flow rate was much greater than that of egg density; reliable model of the incubation percentage concerning the two factors was established, the model had excellent capability for projection with other factors held invariable in this study; the optimal factorial combination was derived through model optimization, i.e., water flow rate 7.66 L min−1/egg density 1.44 × 104 eggs L−1, at which the incubation percentage peaked, 95.9%, with the desirability as high as 95.2%. The incubation percentage was validated to reach 95.12% under the optimal two-factor combination. Currently this optimal factorial combination has been applied to the commercial incubation of Nile tilapia.