Determining the optimum conditions of rearing Labidochromis caeruleus according to the evaluation of environmental parameters: temperature, acidity and carbonate hardness of water

This study was designed to determine the effects of temperature, pH and dKH on growth performance indices of Macro (Labidochromis caeruleus). In each aquarium, 3 fishes were entered randomly with the weighted average: 0.31 ± 0.05 gr and were fed, 5% of biomass twice daily. After 2 weeks adapting, In two intervals,1-25 days and 25-40 days, the biometric measurements were done and growth indices were calculated. In the end, weighted average of fishes was 0.75 ± 0.05 gr. In each aquarium, there were specific combinations of temperature, pH and dKH, using response surface method by Design Expert 7.0, and in total 14 combinations of factors each with 3 replications. According to the results, the combinations of temperature 26˚c, pH: 7.5 and 7 dKH had the best effect on fishes. Studying growth patterns showed that the best mathematical model to show the changes of growth indices was the quadratic equation. The interactions between pH × temperature, and dKH, was more effective on weight changes. At the first time interval, the optimum conditions were 26˚c, pH 7.5 and dKH 7.97-8.2, and at the second period, the optimum conditions were a combination of 25.37-25.62˚c, dKH 8.2-8.35 and pH 7.5-8.25. The optimum temperature to have the least FCR, was 27.67˚c, dKH: 7.65-8 and pH: 6.7-8. Besides, none of the linear, quadratic and cubic equations, represents the length growth of Macro fishes. Therefore, the results of this study, determined the optimum conditions of rearing this species according to the three mentioned parameters.