| dc.description.abstract | In Bangladesh cage culture began in a trial basis at various research institutes and
universities in the late 1970’s (DoF, 1991). Now a days, river based cage culture are
getting popularity in different places of Bangladesh. However, information related to
water quality and production performance of river based tilapia farming is scanty. The
experiment was carried out for a period of nine months from February to October 2017 in
nine experimental cages situated in Atrai river. Several limnological parameters such as
physical (air and water temperature, transparency, water level), chemical (dissolved
oxygen, alkalinity and pH) and biological (phytoplankton and zooplankton) were observed
from three treatments. Sample was collected fortnightly from each treatment. Collected
samples were analyzed in the laboratory of Department of Fisheries Management, Faculty
of Fisheries, Hajee Mohammad Danesh Science and Technology University, Dinajpur.
ANOVA showed a significant variation (P<0.05) in physico-chemical parameters among
the treatments. pH was significantly variable among the treatments. A total of 68 genera of
plankton were identified of which 56 genera was phytoplankton and 12 genera was
zooplankton. Phytoplankton was dominated by chlorophyceae and zooplankton dominated
by rotifera. Stocking density was considered one of the important factors which was
affecting the fish growth. Tilapia fry with an average weight of 61.21 ± 21.41 g, 57.74±
18.83g and 56.18 ± 24.95g (mean ± SD) were stocked in 9 floating net cages (6.1 m × 3.04
m × 1.5 m) in T1, T2 and T3. After 270 days of the experiment, growth in terms of weight
gain, percent weight gain, average weight gain, specific growth rate of fish, survival rate
and production were significantly higher in treatment 1 than those of treatment 2 and
treatment 3. Gross and net production were higher 288.26 kg and 257.66 kg in treatment 1.
The results concluded that lower stocking density was the best for tilapia culture in cages
on the basis of growth which might be technically feasible and economically viable. The
findings of the study will be helpful for selecting the optimum suitable stocking density of
tilapia fish in river based cage farming. Moreover, the result of the study may be provided
some valuable information of the water quality and production performance of tilapia in
cage culture. | en_US |
