Mean DO concentrations inside and at the outlet of the tanks over
the ALFP under the four treatment combinations are shown in Table 1.
Pair-wise comparisons among these values showed that under the same
oxygen treatment, DO concentrations in tanks with big fish were
significantly higher than in tanks with small fish (Pb0.001); however,
all the differences were smaller than 0.45 mg L−1. In the same fish
weight class, DO concentrations in high DO tanks were significantly
higher than in low DO tanks (Pb0.001); the differences were in the
range of 2.62–2.72 mg L−1. There was no interaction effect of fish size
and DO level on DO concentrations (PN0.5). Because the DO concentrations
measured inside and at the outlet of each tank at the same
time were highly correlated under all treatment combinations (rN0.98)
and the difference between them were small (95th percentile of 3231
cases being 0.32 mg L−1), only DO concentrations inside the tanks
were used for all the following presentations and analyses.