Heavy metal accumulation in the muscles of three farmed cyprinid fish species in the City of Basrah

Water pollution may have a significant and negative impact on aquaculture because of heavy metal accumulation. This study aimed to determine the concentrations of heavy metals copper, cadmium, cobalt, iron, manganese, and nickel in the muscles of three cultured fish species viz. Cyprinus carpio, Ctenopharyngodon idella, and Hypophthalmichthys molitrix) in Basrah as well as in water and sediments. Between November 2020 and October 2021, the fish with an average length of 30.5cm and a weight of 379.5g were collected. Based on the results, the maximum concentrations of Fe, Ni, and Cu in common carp were 50, 19, and 10μg/g dry weight in November and December, respectively, while the lowest of Cd, Co, Cu, and Mn were non-sensitive in April. The greatest concentrations of Fe, Ni, and Cu in grass carp were also recorded, 35, 24, 11μg/g dry weight, respectively, in September and October, and the lowest Cd was in April at 1μg/g dry weight. The highest concentrations 53, and 27μg/g dry weight of Fe and Ni in silver carp were found in April, and the lowest in September and October. The heavy metals concentration levels in water varied for Co at 1.13 μg/g dry weight, in July and August for Fe and Ni at 28.87, and 14.93μg/l, respectively. The lowest concentrations were recorded in March for Cd and Mn 0.83, and 0.42μg/L, respectively, whereas Co was non-sensitive. Mn in sediments were highest in December and February at 209.0μg/g dry weight, whereas Cu was lowest in September and October at 21.46μg/g dry weight. The highest levels of heavy metal concentrations in the studied fishes were greater than the internationally permitted limits.