The copper accumulation in liver and gill tissues of Oreochromis niloticus, exposed to 2 ppm Cu and 1g/L clinoptilolite singly and to the same concentrations of their mixture over 24, 48, 72 and 96 hours was studied. ICP-AES spectrophotometer techniques were applied in determining tissue copper levels. Statistical evaluation of the experimental data was carried out by Student Newman Keul’s procedure. No mortality was observed during the experiments. Copper accumulation was lower in metal-clinoptilolite mixture group than metal singly group in gill tissue while no accumulation in both experimental groups in liver tissue (P<0.05). In addition, the copper level in the liver was lower in all experimental groups than in the control (P<0.05). Low Cu accumulation in gill tissue exposed in mixture groups can be explained by copper adsorption with chelating agent. The decrease of Cu reserves in the liver can be expressed by increase of copper-containing enzyme and protein synthesis.