of the control net pen at the beginning of the
experiment. The difference in the mean body
weight between the experimental net pen
and the control net pen was not statistically
significant (p = 0.15, Mann–Whitney’s U test,
n = 30). The fish grew faster with almost
the same growth rate as the fish reared in
the experimental net pen for 50 days (The
growth rates of fish in the experimental
net pens were 1.19 and 1.21, respectively,
while that in the control net pen was 1.11).
The body weight of the fish reached 1.61 ±
0.21 kg in wet weight 50 days later from the
start, which was 0.22 kg heavier than that
in the control net pen. The difference of the
mean body weight between these two net
pens already became statistically significant
(p < 0.01, Mann–Whitney’s U test, n = 30).
Thus, DO control of the water in the net pen
using the microbubble generator can bring a
remarkable acceleration of growth to the fish.
Conclusion:
The results suggested that oxygen saturation
levels affect the growth performance of fish
(red seabream) and bivalves (oysters) in
AgriKultuur |AgriCulture
general. The maximum growth rate and lowest
feed conversion ratio for fish can be attained
at higher oxygen saturation levels between
90% and 120%. However, more research is
needed in order to know at which saturation
point the growth is maximized for individual
aquaculture species.
A nanobubble generator can increase the
dissolved oxygen in the cultivation media
from the initial DO level to a much higher level
up to 30 ppm as was tested in Stellenbosch
previously.
Regarding future experimental work, the
results of these trials should be reconfirmed
and given more time so that more
observations can be made. The actual oxygen
saturation point at which a fish species has a
maximum growth should be identified, hence
more experimentation is needed.
E-mail: [email protected]
Pictures from Google images.
17