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Effect of stocking density
on tilapia (Oreochromis niloticus Linnaeus 1757)
growth and survival in bamboo – net cages trial
S. A. Osofero1, S. O. Otubusin2 and
Daramola J. A.1
1Biological
Sciences Department of the Bells University of Technology,
Ota, Ogun State, Nigeria.
2Department
of Aquaculture and Fisheries Management, University of
Agriculture, Abeokuta, Ogun State, Nigeria.
*Corresponding author. E-mail:
digibebi@yahoo.com.
Tel:
234(0)8025448240.
Accepted
1 March, 2007 |
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The
study was carried out to evaluate the effect of varying
stocking densities on the growth, survival, and yield of
tilapia (Oreochromis niloticus Linnaeus 1757)
at the freshwater reservoir (average depth, 1.7 m) of the
University of Agriculture Abeokuta, Nigeria, for a period of
3 months. Tilapia juvenile with a mean weight of 29
±
4.81 g were randomly (Complete Randomized Design) stocked at
50, 100, 150 and 200 specimen per cage (1 m3)
were fed with commercial feed (34.55% Crude Protein). 20% of
stocked fish was sampled for growth forthnightly. Profit
index of the fish harvested under each treatment was
evaluated. Relevant physico-chemical parameters like pH,
conductivity, temperature, water depth and dissolved oxygen
were also monitored forth nightly. The experimental fish and
fish carcass (before the experiment and at harvest) from
each treatment were analysed in replicates for their
proximate composition. There were no significant differences
(P > 0.05) in daily weight gain, specific growth rate, final
weight, relative growth rate, feed conversion ratio (FCR),
survival, protein efficiency ratio for all the treatments.
However there were significant differences (P < 0.05) in
fish production (harvest), profit index, crude protein,
crude fat, and ash composition of the fish carcass (at
harvest). As stocking density increased, the crude protein
content of the fish carcass decreased indicating an inverse
relationship. The stocking density of 150 juvenile/cage with
a final weight of 82.74 g per fish, feed conversion ratio of
2.15, survival of 99.35% and fish production of 24.79
kg/cage was considered best on the basis of the profit index
of 2.01 compared with the range of 1.45 to 1.82 for the
other three treatments.
Key
words: Stocking density, profit index, survival, growth. |
