The objective of the present study was to investigate the concentration of some heavy metals in the dorsal muscle, gills, and liver of common carp (Cyprinus carpio) from the Dukan lake, Suleimani, Iraq, and its relationship with fish protein content. The sampling was carried out in both the summer and winter seasons of 2021. Fish samples were collected from the water of Dukan lake. Biometry analysis and determining of protein content were carried out. Moreover, the heavy metal concentrations were measured in different tissues and organs of fish (the dorsal muscle, gills, and liver). The metal concentration varied considerably among different tissues and organs. Overall, the mean metal concentration revealed an order of Zn > Fe > Cr > Cd > Cu > As > Pb. The mean concentrations of Zn and Pb were determined as the maximum and minimum concentrations of metals in the fish organs, respectively. Metal accumulation was higher in the gills and liver than in the muscle (except Cr). The content of protein showed a close relationship with some of the metal concentrations. The concentrations of metals like As, Cd, and Cu were higher during the summer than in the winter, except for Cr and Fe. Due to the concerns related to the adverse effects of heavy metals in fish meat on human health, investigation of the concentration of pollution and regular monitoring of the physicochemical and heavy metal contents and its relationship with those measured in fish is strongly recommended.