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International Journal of Aquaculture, 2014, Vol.4, No.02,
http://ija.sophiapublisher.com
3
egg yolk and rotifer was between the two diets.
Contrasting the 1
st
phase, in this phase the larvae fed
with rotifer indicated the poorest survival (54%)
(Table 2).
Table 2 Growth rate, SGR, and survival percentages of
Clarias
gariepinus
larvae fed with chicken egg yolk, rotifer
(
Brachionus plicatilis
), and a mixture of the two during the 2
nd
phase of the experiment
Egg yolk
Egg yolk
+ Rotifer
Rotifer
Initial average
weight(mg)
13.39 ± 2.87 10.45 ± 1.80 7.62 ± 2.45
Final
average
weight(mg)
19.85 ± 3.66 13.99 ± 1.74 11.99 ± 1.69
Initial average
length (mm)
9.65 ± 1.16
8.95 ± 0.59
8.20 ± 0.42
Final
average
length (mm)
12.13 ± 0.60 10.76 ± 0.78 10.87 ± 0.67
Growth
rate
(%/day) (sd)
4.83
a
3.38
b
5.73
c
Survival
(%)
(nsd)
61
a
63
a
54
a
SGR(nsd)
0.08
a
0.06
a
0.09
a
Condition factor
(CF) (nsd)
1.11
a
1.12
a
0.93
a
Note: Values with same superscript in a row means that were
not significant different
There was significant variation in water quality
parameters as measured in the different feed treatments
(One–Way ANOVA with Tukey’s HSD post hoc test,
F=1673,p<0.01, Table 3). DO indicated a range (lowest
to highest) of 5.31±0.61 to 6.30±0.14 mgO
2
L
−1
.
Temperature and pH indicated ranges of 21.53±0.11
to 24.30±0.42
℃
and 5.65±0.21 to 6.79±0.24,
respectively.
The rotifer
B. plicatilis
had the highest crude protein
content (25.11%) followed by egg yolk
(15.95%)
(Table 4).
2 Discussions
The rotifer
B. plicatilis
indicated the poorest growth
rate in the larval rearing of African catfish while
chicken egg yolk performed the best. We attribute this
finding with the fact that
B. plicatilis
are very small in
size as compared to the mouth size of the African catfish
larvae at commencement of their exogenous feeding
period. The rotifers which had higher crude protein
Table 3 The pH, temperature, and dissolved oxygen (DO) as
measured in the tanks with different feed treatments during the
1
st
and 2
nd
phases of the experiment n = 14
Parameter Morning
(8.30hr)
Afternoon
(1.00hrs)
Evening
(4.00hrs)
Feed
type
pH
nsd
6.01 ±
0.35
6.76 ±
0.21
5.70 ±
0.14
Rotifer
6.10 ±
0.36
6.79 ±
0.24
5.90 ±
0.28
Egg
yolk
5.77 ±
0.40
6.66 ±
0.19
5.65 ±
0.21
Egg
yolk
+Rotifer
T(
℃
)
sd
21.53 ±
0.11
23.62 ±
1.37
24.00 ±
0.10
Rotifer
21.97 ±
0.40
23.91 ±
0.84
24.30 ±
0.42
Egg
yolk
21.87 ±
0.11
24.08 ±
0.92
24.25 ±
0.35
Egg
yolk
+Rotifer
DO
sd
5.67 ±
0.40
5.36 ±
0.80
5.70 ±
0.14
Rotifer
5.53 ±
0.12
5.31 ±
0.61
5.89 ±
0.35
Egg
yolk
5.90 ±
0.35
5.34 ±
0.62
6.30 ±
0.14
Egg
yolk
+Rotifer
Note: nsd = not significant different while sd = significant
different
Table 4 Proximate analysis of egg yolk and the rotifer
B.
plicatilis
Feed
Crude
protein
(%)
Lipids
(%)
Carbo-
Hydrate
(%)
Dry
matter
(%)
Ash
(%)
Egg yolk
15.95
3.62
4.09
47.75
3.14
B. plicatilis
25.11
5.36
3.51
64.32
16.45
than egg yolk, if not the constrain of size then would
have been expected to perform better than egg yolk.
According to Lubzens et al. (2001), when using
rotifers as a feed, normally the number of rotifers
consumed would determine the quantity of food
reaching the gut of the larva. In our case, the larvae
fed with rotifers possibly spent most of their time
eating while having only little of the food reaching
their guts for translation to growth. Generally, rotifers
are worldwide appreciated as good starter feed for the
rearing of most marine fish larvae (i.e. codfish) which
are small in size during commencement of their
exogenous feeding (Lubzens et al., 2001; Yilmaz et