Optimizing the condition of rearing Astronotus ocellatus using statistical method Central Composition Design (CCD)

This study was designed to determine the effects of parameters: temperature, pH and dKH on growth indices of Oscar fish (Astronotus ocellatus). For this purpose, in each aquarium, there was specific combinations of temperature, pH and dKH, using design of experiment with Design Expert 7.0, and in total 14 combinations or treatments, each with 3 repetitions and thus, 3 fishes were entered in each aquarium randomly. In timespan 1-30 days, the measurement of body weight and body length was done, and growth indices including: weight gain (WG) and length gain (LG) were identified. Studying of growth pattern showed that the best mathematical model to show the changes of growth indices was quadratic equation. Carbonate hardness had the most effects on weight changes. The optimum temperature was 23-26˚c, pH was 6.7-8.3 and dKH was 5-6. Growth pattern according to length gain, was quadratic equation. Carbonate hardness had the most effects and the optimum range was similar to optimum condition for weight gain.