Bioaccumulation of heavy metals in different tissues of Nile tilapia (Oreochromis niloticus) in Bangladesh

Introduction: The culture of Nile tilapia (Oreochromis niloticus) has become wide spread because of its high productivity over a short period of time.Its production partially fulfills the demand for food in rural people in Bangladesh.However, the accumulation of toxic heavy metals in the human body through consumption of fish contaminated by it causes various diseases.The aim of this study was to evaluate the bioaccumulation of five heavy metals, namely, cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni) and copper (Cu) in cultured Nile tilapia in the Noakhali region of Bangladesh.Methods: Fish were collected from three different fish farms in the Noakhali region and samples of gill, muscles and liver of tilapia were assayed for Cd, Cr, Pb, Ni and Cu using atomic absorption spectroscopy.Proximate composition of the tilapia was also determined.Results: Metal accumulation in different tissues was as follows: liver > gill > muscle.The accumulation of metals in the muscle, gill and liver was Ni > Pb > Cr > Cu > Cd, Pb > Ni > Cu > Cr > Cd and Pb > Cu > Ni > Cr > Cd, respectively.The bioaccumulation of lead was significantly increased in liver and gill while muscle showed the lowest value.Conclusion: It can be concluded that bioaccumulation of Pb, Cr and Ni in Nile tilapia in this study exceeds the permissible limits set for heavy metals by Food and Agriculture Organization (FAO) and International Atomic Energy Agency (IAEA)-407.This is potentially risky for consumers.