In experiment 1, groups of fish (5-6 fish/group) were exposed for 24 h to 0.1-600 nM Cd at three Zn concentrations( 2, 4 and 16 µM) . In experiment 2, four groups of fish (6 fish/group) were exposed for 24 h to 0.1 nM Cd at four Zn concentrations (0, 2, 4 and 16 µM) . Another four groups of six fish each were exposed to 30 nM Cd at the same Zn concentrations. In experiment 3, groups of six fish each were exposed for 24 h to 0.1-30 nM Cd and 0 or 2µM Zn.