Analysis of mean DO concentrations at six times per day over the
whole ALFP and mean DO concentrations at 25 times in four 24-hour
periods (Fig. 1) showed that there were effects of time and interaction
effects of time and size and of time and oxygen on the diurnal
variations in DO concentrations (Pb0.001). There was an abrupt
change in DO concentrations from the time just before feeding to the
time right after feeding (Fig. 1); these changes were significantly larger
in tanks with small fish than with big fish at the same DO level
(Pb0.05) and significantly larger in low DO tanks than in high DO
tanks in the same weight class (Pb0.001). Mean DO concentrations in
the tanks with small fish showed a declining trend throughout the
ALFP while DO concentrations in the tanks with big fish declined
during the first 2 weeks and were almost constant during the last week