International Journal of Aquaculture, 2015, Vol.5, No.3 1
-
13
5
Changes in average body weight (g /fish) of Nile
tilapia reared in concrete tanks for 44 weeks at
different stocking density and water exchange rate are
shown in Figure 1. It is evident from this figure that at
the beginning of the experiment, average initial weight
(g/fish) was not significantly different among the
densities at two water exchange rates (P > 0.05). The
over all average
SE of mono-sex Nile tilapia was 7.5
1.2 g/fish. At the termination of the experiment, the
mean body weight ranged between 220.9
10.9
and
130.0
6.5 g/fish for the lowest (50 fish/m
3
at 8 L/min.)
and the highest (100 fish/m
3
at 8 L/min.) stocking
density, respectively (Figure 1).
Figure 1 Changes in average body weight (g /fish) of Nile
tilapia reared in concrete tanks for 44 weeks at different
stocking density and water exchange
Changes in average body length (cm /fish) of Nile
tilapia reared in concrete tanks for 44 weeks at
different stocking density and water exchange rate are
shown in Figure 2. It is evident from this figure that at
the beginning of the experiment, average initial length
(cm/fish) was not significantly different among the
densities at two water exchange rates (P > 0.05). The
over all average
SE of mono-sex Nile tilapia body
length was 8.9
0.1 cm/fish. At the termination of the
experiment, the mean body length ranged between
22.6
0.6 and 19.0
0.3 cm/fish for the lowest (50
fish/m
3
at 12 L/min.) and the highest (100 fish/m
3
at
12 L/min.) stocking density, respectively (Figure 2).
Effects of stocking density and water exchange rate on
mono-sex Nile tilapia,
O. niloticus
gain in weight
(g/fish), gain in weight (%), gain in length (cm/fish),
gain in length (%) after 44 weeks of rearing in
concrete tanks in the present study are presented in
Figure 2 Changes in average body length (cm/ fish ) of Nile
tilapia reared in concrete tanks for 44 weeks at different
stocking density and water exchange rates
Table 3. It is evident from this table that, average gain
in weight (g/fish), average gain in weight (%), average
gain in length (cm/fish) and average gain in length (%)
were affected significantly (P ≤ 0.01) by stocking
density but not influenced by water exchange rate.
The highest average gain in weight (g) and gain in
length (cm) of fish were recorded with the lowest
stocking density (50fish/m
3
) and the lowest were
recorded in the highest stocking density (100fish/m
3
).
The lowest stocking density grows faster and had 11.5
folds more than the highest stocking density. There
were no significant interaction between stocking
density and water exchange rate. There were a
correlation between stocking density and average gain
in weight (g/fish) and average gain in length (cm/fish).
When the stocking density were increased the average
gain in weight and average gain in length of fish were
decreased.
Effects of stocking density and water exchange rate on
mono-sex Nile tilapia,
O. niloticus
average daily gain
(g/fish/day), specific growth rate (% /day) and
condition factor (K) after 44 weeks of rearing in
concrete tanks are presented in Table 4. It is evident
from this table that, average daily gain (g/fish/day)
and specific growth rate (%/day) were affected
significantly (P ≤ 0.01) by stocking density but not
influenced by water exchange rate. The highest
average daily gain (g/fish/day) and specific growth
rate (% /day) were recorded with the lowest stocking
density (50fish/m
3
) and the lowest were recorded in
the highest stocking density (100fish/m
3
). The lowest
