Water temperature was measured every day, and water quality measured every week. During the test period the water quality on average was as follows: water temperature 24.5 4.32 C, DO > 5 mg L1,NH3 < 0.05 mg L1, H2S < 0.1 mg L1
, pH 8.0e8.2. The feeding amount increased every other week and the amount was adjusted according to body weight measurement every two weeks.