Growth performance of common carp, Cyprinus carpio, fry at different experimental stocking densities in the environmental conditions of central Iraq

This study aimed to examine the growth performance of common carp, Cyprinus carpio, fry in different stocking densities in the environmental conditions of central Iraq. The experiment was performed for 60 days at the central fish hatchery in the Suwayra district, the Kut Province. The study examined four groups: three with different stocking densities (1 million (T1), 1.5 million (T2), and 2 million (T3) fry per hectare) and a control group (T0) without supplementary feeding. The fry were reared in earthen ponds, with water quality parameters constantly monitored and maintained within optimal conditions. The results revealed that stocking density significantly impacted growth performance and survival rates. T2 exhibited the highest survival rate (84.91%) and the greatest final average weight (8.23 g). Furthermore, T2 displayed the highest specific growth rate (SGR) and daily weight gain (DWG), suggesting that this stocking density is optimal for the prevailing conditions in central Iraq. The economic analysis revealed that T2 had the highest profitability, with a benefit-cost ratio (BCR) of 1.2, followed by T1 (BCR = 1.18) and T3 (BCR = 1.00). Feed expenses accounted for the majority of total costs, emphasizing the importance of efficient feed management. The findings underscore the importance of maintaining optimal stocking densities and implementing effective feeding strategies to enhance growth performance and economic sustainability in common carp farming in Iraq.