Implication of Thermal-Unit Growth Coefficient of the Common Carp (Cyprinus carpio L.) in Different Water Temperatures

The present study was conducted in the Fish Feeding laboratory at the College of Agriculture, University of Basra, to estimate the thermal unit growth coefficient of common carp (Cyprinus carpio) at different temperatures. The experiment extended from December 16 till the 1^st of June 2022. Three temperatures of 20, 25 and 30°C were determined, and the average values of initial fish weight were assessed with 18.49 ± 2.50, 24.13 ± 3.38, and 19.02 ± 4.72g, respectively. The experiment included three different temperatures, and each treatment was repeated in three replicates. Fish samples were fed on a commercially manufactured diet, with a feed rate of 3% of body weight. The initial weight, final weight, weight gain, relative growth rate, specific growth rate, thermal unit growth coefficient and feed conversion rate were calculated. For the specific growth rate, the thermal unit growth coefficient and the feed conversion ratio, the highest values were obtained at a low temperature of 20°C; the values of these parameters were 0.73%/ day, 0.37 and 3.94, respectively. It was concluded that in temperatures between 20 and 30°C, no effect was detected on the growth of common carp. This temperature range was considered optimal for growth, achieving good growth rates for common carp fish.