KONINKLIJKE ACADEMIE VOOR OVERZEESE WETENSCHAPPEN ...

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3.1.4.5. Experiment 3: Mean Growth of Fish in Intensive Pond Culture System
— Water Quality Parameters in Intensive Culture Systems
Figure 9 shows that DO concentrations in intensive culture systems ranged
from 4.5 to 6.25 ppm and 4.25 to 5.25 ppm for treatment I and II respectively,
the average content of DO in treatment I (4.83 ±1.13 ppm) was higher (p < 0.05)
than in treatment II (4.5 ± 0.53 ppm). However, the acceptable DO for climbing
perch was reached ( K ie m 2000).
Time (months)
* Treatment I —■— Treatment II
Fig. 9. — Fluctuation of DO concentrations in intensive culture system.
The ammonium concentrations in intensive systems ranged from 0.8 to
1.7 ppm and 0.9 to 2.8 ppm for treatment I and II respectively (fig. 10). The average
of ammonium in treatment I (1.53 ± 0.4 ppm) was lower (p < 0.05) than
treatment II (0.91 ± 0.71 ppm). However, these values are still acceptable for fish
growth.
The P-P0 4 3 concentrations in intensive culture system were high (fig. 11).
P-PO4 3 ranged from 0.11 to 0.5 ppm in treatment I, and the average of P-PO4 3
in treatment I was 0.13 ± 0.09 ppm. P-PO43 ranged from 0.35 to 1.03 ppm
in treatment II and the average of P-P04 3 was 1.03 ± 1.46 ppm. There were
significant differences (p < 0.05) between the treatments. According to P h u
(2000), suitable P-PO4 3' in pond culture ranged from 0.1 to 0.3. In comparison
with our result, the P-P04 3' values were suitable for fish growth in the culture
system.
The results presented in figure 12 show that COD content in treatment I
ranged from 13.57 to 16.93 ppm, the average of COD was 13.6 ± 2.9 ppm. These