The effect of recirculating aquaculture systems on the concentrations of heavy metals in culture water and tissues of Nile tilapia Oreochromis niloticus

► Concentration of As, Fe, Mn, Ni, and Zn in RAS water increases with decreasing water exchange rates. ► Accumulation in the water is not translated into accumulation in the fish liver and muscle. ► Accumulation of heavy metals is higher in the liver as compared to the muscle, except for As. ► Concentration of heavy metals in fish produced in RAS is lower than permissible safety levels for human consumption.