Preferential feeding on high quality diets decreases methyl mercury of farm-raised common carp (Cyprinus carpio L.)

► Common carp of semi-intensive aquacultures feed on natural and artificial food sources. ► Main dietary sources of methyl mercury of cultivated common carp are identified. ► Carp actively select diets of highest biochemical quality. ► Carp preferentially feed on artificial diets based on marine fish oils. ► Artificial diets reduce methyl mercury accumulation of cultivated common carp.