KONINKLIJKE ACADEMIE VOOR OVERZEESE WETENSCHAPPEN ...

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ment I (85.5 %). Finally, the total fish biomass of 24,600 kg/ha obtained in treatment
II (50 fish/m2) was higher than that in treatment I (30 fish/m2) of
21,300 kg/ha. Regarding the different fish body weight, survival rate and the
total fish biomass in these treatments, higher fish stocking density (50 fish/m2) in
treatment II was the main factor to increase the amount of ammonia excreted by
fish, leading to a reduction in water quality and fish growth in intensive culture
systems (T u c k e r & B o y d 1985).
3 .4 . H ousehold I ncom e F inancial A nalysis for I n ten sive C ulture S ystem
The household financial results in table 12 show that, although the fish yield
in treatment II (50 fish/m2) was higher than in treatment I (30 fish/m2), the net
farmer’s income of 284,525,000 VND/ha obtained in treatment II was higher
than in treatment I of 266,370,000 VND/ha (30 fish/m2). However, the cost ratio
benefit and the cost ratio profit in treatment II (1.56 and 0.56 respectively) were
lower than in treatment I (1.64 and 0.64 respectively). Therefore, treatment I at
Table 10
Growth of climbing perch in intensive culture system in ponds at two stocking densities
Treatments Parameters I. (30 fish/m2) II. (50 fish/m2)
Initial weight (g) W 5.2 ± 1.2 5.2 ± 1.2
W 20.5 ± 1.8 15.7 ± 3.1
Weight after 60 days DW 0.3 0.2
SGR 2.3 1.8
W 33.8 ± 2.3 22.1 ± 1.8
After 90 days DW 0.3 0.2
SGR 2.1 1.6
W 42.6 ± 1.7 38.3 ± 2.3
After 120 days DW 0.3 0.3
SGR 1.8 1.7
W 63.2 ± 3.4 52.7 ± 4.6
After 150 days DW 0.4 0.3
SGR 1.7 1.5
W 71.5 ± 3.5 66.4 ± 2.8
After 180 days DW 0.4 0.3
SGR 1.5 1.4
Survival rate (%) 85.5 74.4
Table 11
Yield of climbing perch in intensive culture system in ponds at two stocking densities
Items I. (30 fish/m2) II. (50 fish/m2)
• Fish yield/fish pond (kg/fish pond) 575 8,610
• Fish yield/ha (kg/ha) 21,300 24,600