In the present study plants of Ceratophyllum demersum L. was collected and grown for six months in large hydrophobic tubes. The effect of zinc ion concentration was studied at different concentration on plant; for 7 days in 10 per cent Hoagland media. After day 1 no significant effect was observed on plant for all concentration of zinc. After day 2, 3 and 4 change in colour from green to yellow was observed with different colour intensity. It was observed that after day 5, 6 and 7 the leaves of Ceratophyllum demersum L. become black in colour, the intensity of blacking in colour was increased as concentration of zinc ion increased.The plant showed maximum accumulation of cadmium after 7 day at 20µM concentration.The maximum level of thiol compound was observed at 10µM after 3 days. The maximum level of cysteine synthetase was observed at 10µM after 3 days. The maximum level of glutathione-S-transferase was observed at 10µM after 4 days. The maximum level of glutathione reductase was observed at 10µM after 4 days. The plant showed maximum accumulation of arsenic after 7 day at 20µM concentration. The maximum level of cysteine concentration was observed at 15µM after 4 days. The maximum reduced glutathione concentration was observed at 10µM and 20µM, respectively.