Ozonation of water ammonia could get high eff iciency in the presence of bromide and was applied in many industry areas for treatment of waste water. In order to apply the method to treat fresh aquaculture waste water, it is necessary to investigate the effects of bromide on growth, thyroid hormones and its accumulation in tissues of fresh water f ish, and evaluate its safety. In our study, we chose the most general culture species of common carp ( Cyprinus carpio) as research object . The experiment was carried out in a group of 14 recirculating water culture tanks with 0. 5m3 volume of water, 18 f ish for each tank. During experiment, the f ish were fed with pellet food and the culture water was exchanged per 3 days. The added chemicals were NaBr and NaCl. The dissolution concentration of 6 test groups were 5mg#L - 1 NaBr, 15mg#L - 1 NaBr, 25mg#L - 1 1NaBr, 5mg#L - 1 NaBr 0. 1% NaCl, 5mg#L - 1 NaBr 0. 3%NaCl and 5mg#L - 1 NaBr 0. 5%NaCl and f resh water without any chemical was taken as control group. The common carp was examined in dif ferent concentration of NaBr and NaCl in fresh water. Growth rate and accumulation of bromide in different organs/ tissues were studied on 15, 30 and 45d respectively. At the same time, thyroid hormone was determined on 45d. The research showed that the growth rate of common carp could be promoted by adding NaBr in water and the difference of growth rate was signif icant in 15mg#L- 1NaBr ( P< 0. 05) comparing with the control group. Although the growth rate of all test groups was faster than control group, adding NaCl would decrease the growth rate. Thyroid hormone of test groups was increased and it reached to maximal value in 15mg#L- 1NaBr ( P < 0. 01) . The effect of bromide on growth was in accordance with the concentration of thyroid hormone, but adding NaCl could not af fect the concentration of thyroid hormone. The accumulation of bromide was higher in liver and skin, and kept high level in kidney in all concentrations. The accumulation of bromide was 72. 40mg#L - 1 in muscle at 25mg#L - 1 NaBr. The accumulation of bromide could be decreased significantly in different organs/ tissues if NaCl was added ( P< 0. 01) . It was secure to aquatic life of freshwater when concentration of NaBr in water was lower than 25mg# L - 1 , and the accumulative amount of bromide in aquatic life of freshwater accorded with food health standard for human being . Based on the result, we can determine the adding concentration of bromide in aquaculture waste water treatment . So it is po ssible for us to ozone ammonia in fresh aquaculture by adding catalytic bromide and the ozonation of ammonia would provide new treatment technology of fresh aquaculture water.