International Journal of Aquaculture, 2013, Vol.3, No.23, 133
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137
http://ija.sophiapublisher.com
134
more expensive than local plant extracts; also their
administration in fish is time-consuming and
labour-intensive and requires expertise. Further,
synthetic hormones accumulate in the sediment water
and aquatic biota (Cek et al., 2004) and there are
concerns about consumer perceptions of eating
hormone treated fish (Phelps and Carpenter, 2002).
Tribulus terrestris
is known to elevate the testosterone
levels in humans and animals. In humans, it has been
used to treat impotence and has been found to increase
testosterone levels (Adaikan et al., 2000; Gauthaman
et al., 2002).
T. terrestris
contains protodioscin, a
saponin, which is considered the main substance
responsible for increasing testosterone production
(
Ganzera et al., 2001). There is no report on the
accumulation of protodioscin in the sediment water or
on the toxicity of
T. terrestris
in fish. An alternate
technique for commercial production of all-male fish
populations would be to use plant extracts.
The objective of this study is to determine the effect of
the extract of
T. terrestris
on sex reversal in
O.
niloticus
larvae.
1
Results
Table 1Growth parameters of
O. niloticus
under different levels of
Tribulus terrestris
extract in the laboratory
T
1
T
2
T
3
T
4
T
5
T
6
Initial weight (g)
0.03
±0.0012
a
0.03
±0.0011
a
0.03
±0.0011
a
0.03
±0.0010
a
0.03
±0.0013
a
0.03
±0.0011
a
Initial length (cm) 0.6±0.0013
a
0.6
±0.0012
a
0.6
±0.0011
a
0.6
±0.0013
a
0.6
±0.0012
a
0.6
±0.0012
a
Final weight (g)
0.76
±0.028
a
0.82
±0.030
ab
0.85
±0.032
ab
0.95
±0.037
b
0.98
±0.036
b
0.77
±0.029
a
Final length (cm)
4.5
±0.36
a
4.9
±0.39
a
5.5
±0.43
ab
5.8
±0.53
ab
6.0
±0.62
c
4.8
±0.39
a
Weight gain (g)
0.73
±0.08
a
0.78
±0.09
ab
0.82
±0.09
ab
0.92
±0.1
b
0.95
±0.11
b
0.74
±0.08
a
FCR
2.12
±0.14
b
2.03
±0.17
b
1.89
±0.21
ab
1.7
±0.36
a
1.53
±0.17
a
2.056
±0.10
b
SGR
14.48
±0.15
a
14.59
±0.19
a
14.75
±0.24
ab
15.08
±0.50
bc
15.26
±0.25
c
14.55
±0.12
a
Survival
81.3
±2.31
a
80
±4.00
a
80
±4.00
a
85.3
±2.31
ab
89.3
±4.62
b
82.7
±2.31
a
Note: Means with the same superscript along the row are not significantly different (p<0.05)
Table 2 Growth parameters of
O. niloticus
under different levels of
Tribulus terrestris
extract in the pond
T
1
T
2
T
3
T
4
T
5
T
6
Initial weight (g) 0.76±0.028
a
0.82
±0.030
ab
0.85
±0.032
ab
0.95
±0.037
b
0.98
±0.036
b
0.77
±0.029
a
Initial length (cm) 4.5±0.36
a
4.9
±0.39
a
5.5
±0.43
ab
5.8
±0.53
ab
6.0
±0.62
c
4.8
±0.39
a
Final weight (g)
12.37
±1.37
a
14.62
±1.32
ab
15.96
±1.47
b
17.06
±1.42
c
18.04
±1.8
c
14.83
±1.38
ab
Final length (cm) 11.3±1.26
a
13.8
±1.53
a
15.1
±1.68
ab
16.1
±1.79
b
17
±1.89
b
14.2
±1.58
ab
Weight gain (g)
11.35
±1.26
a
12.18
±1.33
ab
12.94
±1.43
ab
14.14
±1.52
bc
14.29
±1.59
c
12.06
±1.34
ab
FCR
1.4296
±1.34
a
1.303
±1.16
a
1.1356
±0.93
a
0.9768
±0.83
a
0.8554
±0.57
a
1.368
±0.84
a
SGR
5.3150
±2.64
a
5.3242
±2.83
a
5.3618
±2.48
a
5.3032
±2.35
a
5.2968
±2.78
a
5.3582
±2.83
a
Survival
91.8
±3.40
a
91.7
±3.40
a
95
±3.52
b
95.3
±3.53
b
95.3
±3.54
b
90.3
±3.34
a
Sex ratio
Males
33.33
±0.58
a
55.67
±3.06
b
67.67
±2.08
c
79.33
±2.52
d
83.67
±4.04
e
73.00
±1.73
d
Females
66.67
±0.57
e
44.33
±3.05
d
32.33
±2.08
c
20.67
±2.52
a
16.33
±4.04
a
27.00
±1.73
b
Note: Means with the same superscript along the row are not significantly different (p<0.05)
Figure 1 Percentage of male to female
2
Discussion
2.1
Survival Rates and Growth of Fish
Fry and fingerlings in all the treatments of the
experiments exhibited high survival rates, though this
survival was not uniform, it was observed that fish
showed increase in survival rate with increase in
T.
terrestris
level in the feed used in the experiment. This
is similar to the observations of Kavitha and
Subramanian (2011), and Cek et al., (2007a). This