and pH (Emerson et al. 1975). Dead

and pH (Emerson et al. 1975). Dead fish were counted and
weighed at each sampling period (6, 12, 18, and 24 h).
Statistical analysis.—Cumulative mortality (CM) was calculated
as CM
i
=
(WD
i
/WT
i
)100%, where CM
was cumulative
mortality, WD
was weight of dead individuals, and
WT
i
i
was total weight of juveniles, and i was the ith hour.
To determine significant differences between treatments, water
quality variables and fish mortality were analyzed using oneway
ANOVA, followed by least-significant difference (LSD)
multiple-comparisons analysis. Statistical Package for the Social
Sciences (SPSS) Version 15.0 was used as statistical software,
and the significance level for statistical analyses was set
at α = 0.05.
RESULTS
The DO level remained high in all treatments through the
first 12 h of the experiment (Figure 1), but DO at 18 h and 24 h
was significantly higher in MS-222 treatments than in both the
control and clove oil treatments (P < 0.05). The pH declined
sharply during the first 6 h of the experiment, and no significant
differences were observed between control and anesthetic
treatments. However, pH of MS-222 treatments declined significantly
more slowly than in the control and clove oil treatments
after 12 h (P < 0.05; Figure 2).
Total ammonia increased rapidly during the experiment. In
the control group, total ammonia increased from 0.47 mg/L at
the beginning of experiment to 11.01 mg/L (SE, 0.48) at the
end (Figure 3). There were no significant differences in total
ammonia between control and anesthetic treatments before the
initial 12 h, but concentration of ammonia in the control was
significantly higher than in anesthetic treatments at 18 h and 24 h
i