Seawater temperature fluctuated during the experiment and ranged between 20.5 and 30.6C; however, salinity showed no fluctuations and was always approximately 42 g L)1. Dissolved oxygen (DO) in the fish tank ranged from 0.85 to 6.2 mg L)1, whereas the values of DO in the inflow and the outflow of the seaweed tanks was 2.92 and 5.59 mg L)1, respectively. The mean pH value in the fish culture tank was 7.57 and in the seaweed tanks it was 8.04, showing additional CO2 available for photosynthesis as a result of fish respiration. In the fish culture tank