The local farming oysters have been sampled from retailers of two grown area that was keep till 16 July 2012. There are 143 batches of samples were obtained from 16 December 2010 to 25 October 2012. The mean value condition index of shell dry weigh of Chang-Hua was lower Tai-Shi samples. Its minimum mean condition index was 0.020403±0.004341 that was sampled from Chang-Hua retailers and maximum was 0.08419±0.013395. The mean value of 0.020403±0.004341 was the Tai-Shi samples minimum mean condition index and its maximum was 0.08419±0.013395. The oysters reared in upwelling tank that floating on outdoors pond after 34 days gained maximum condition index of 0.08994±0.01873. Its initial value of 0.02842±0.00670 was deducted gained daily increase rate of 6.37％ was not the maximum increase rate and its total increase rate was 216.47％. However, the early value of 0.02842±0.00670 to final of 0.06574±0.01169 through 14 days rearing gained maximum daily increase rate of 9.45％ and its total increase rate was 132.32％. Reared in flow through tank that inadequate of algae was added after 19 days its condition index dropped to minimum of 0.01158±0.004369. Reared in a little algae adding tank the oysters fatness lost severely that half probability was caught in the experiment. The flowing of rearing water arouse spawning of oysters always gave rise to lose fatness. This case was out of control troublesome problem.
Seawater running through UV radiation unit in a small-scale shallow tank system under low temperature of 18 to 21℃ was more efficient depuration for oysters. At higher temperatures, e.g. as high as 31 °C, more viruses are removed from the oysters more quickly but, while most oysters will be died after depurated.