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International Journal of Aquaculture 2012, Vol.2, No.9, 59
-
64
http://ija.sophiapublisher.com
60
1 Results
The mean values of water quality parameters (pH and
dissolved oxygen (DO) concentration) as well as the
growth performance, feed utilization efficiency and
survival rate data of the juvenile
Oreochromis
niloticus
reared at different water temperature are
summarized in Table 1 and Table 2. Similarly, the
growth trends of all groups of fish are given in Figure 1.
All groups of fish increased their growth
performances steadily following exposure to their
respective water temperature treatments. The
physicochemical parameters such as pH and DO
concentration were suitable environmental condition
for rearing juvenile
Oreochromis niloticus
.
Table 1 Mean values of pH and DO concentration measured at
different water temperature
Temperature (
℃
)
pH
DO (mg/ L)
24
8.27a
6.7b
26
8.24a
6.7b
28
8.18a
6.2b
30
8.21a
6.3b
32
8.32a
5.9b
34
8.30a
5.7b
Note: Mean values in the same column having the same letters
are not significantly different (P>0.05)
The highest growth performance of juvenile
Oreochromis
niloticus
in terms of final mean body weight (FMBW),
mean body weight gain (MBWG) and specific growth
rate (SGR) was observed on the fish reared at 32
℃
water temperature followed by 30
℃
as compared with
other water temperature. Similarly, the best feed
utilization efficiency of juvenile
Oreochromis
niloticus
in terms of feed conversion ratio (FCR),
metabolic growth rate (MGR) and protein efficiency
ratio (PER) was observed on the fish reared at 32
℃
water temperature followed by 30
℃
. In all cases the
lowest growth performance and the poorest feed
utilization efficiency of juvenile
Oreochromis
niloticus
were
observed on the fish reared at 24
℃
water temperature, and were significantly different
(p<0.05). In general, the order of growth performance
and feed utilization efficiency of juvenile
Oreochromis niloticus
is 32
℃
>30
℃
>28
℃
>34
℃
>
26
℃
>24
℃
(Figure 1).
2 Discussions
2.1 Physicochemical parameters of water
The growth performance and feed utilization
efficiency of juvenile
Oreochromis niloticus
affected
by different environmental factors such as pH,
nitrogen waste, temperature, dissolved oxygen
concentration and other water quality parameters
(Gjedrem, 1997; Noor et al., 2010). The physico-
chemical parameters such as pH and dissolved oxygen
concentration recorded during the experiment were
not significantly different (p>0.05) and were suitable
environmental conditions for rearing juvenile
Oreochromis niloticus
as mentioned by Saber et al
(2004), Xu et al (2005) and Azaza et al (2008).
Table 2 Mean values of growth parameters of juvenile
Oreochromis niloticus
reared under different water temperature
Note: Mean values in the same row having the same letters are not significantly different (P>0.05)
Temperature (
℃
)
Growth Parameters
24
26
28
30
32
34
Initial mean body weight (g/fish)
4.20a
4.15a
4.27a
4.16a
4.12a
4.21a
Final mean body weight (g/fish)
29.32a
38.59b
45.75c
51.15d
57.24d
43.14bc
Mean body weight gain (g/fish)
25.12a
34.44b
41.48cd
46.99ed
53.12e
38.93c
Specific growth rate ( %/day)
2.16a
2.48b
2.64c
2.79d
2.93d
2.59c
Feed conversion ratio
2.83a
2.56b
2.52b
2.47c
2.43c
2.53b
Metabolic growth rate (gkg
0.8
/day)
2.91a
3.32b
3.55b
3.72c
3.89c
3.47b
Protein efficiency ratio (PER)
0.93a
1.28b
1.54c
1.74d
1.97d
1.44c
Survival rate (%)
100a
100a
100a
100a
100a
100a