International Journal of Aquaculture 2015, Vol.5, No. 41, 1-20
12
tank that received S1P0 to 2.65±0.07mg/l in tank of
fish fed S4P0 (Duncan, P<0.05). Phytase addition
increased significantly the level of dissolved oxygen
in tank fed 75%, and 100% soya bean compared to
diets without phytase (Duncan, P<0.05). Fish reared in
tanks allocated 25% soya bean showed increase in
dissolved oxygen from 3.85±0.07mg/l in S1P0 fish
tank to 3.95±0.07mg/l for tank with fish fed S2P4
(Duncan, P>0.05). The lowest level of dissolved
oxygen were obtained in tanks of fish fed S0P0 and
S3P0, both of which recorded similar value of
2.15±0.07mg/l; tanks with fish fed diets S3P2 and
S3P3, which both had the highest dissolved oxygen
level of 3.95±0.07mg/l. Irrespective of phytase levels,
all soyabean diets showed a significantly higher level
of dissolved oxygen compared to fish meal diet
(Tukey, P<0.05). Dissolved oxygen showed a positive
with phytase (r= 0.262, P>0.05) (Table 12). It also
showed a positive correlation with final weight,
weight gain, feed intake, SGR, PER, and survival rate
(Table 14).
Table 11 Water Quality Analysis
Treatments
Dissolved Oxygen
(mg/l)
pH
Temperature (
0
C)
Ammonia (mg/l)
Nitrate (mg/l)
Initial
4.80±0.02
7.40±0.03
23.8±0.04
0.00±0.00
0.00±0.00
S0P0
2.15±0.07
a
7.44±0.01
abcdef
23.55±0.07
ab
9.39±0.03
r
33.11±0.18
j
S1P0
3.85±0.07
jk
7.45±0.00
bcdef
23.50±0.28
a
4.31±0.01
m
1.70±0.01
b
S1P1
3.75±0.07
ij
7.43±0.00
abcdef
23.80±0.00
bcd
1.83±0.01
h
1.23±0.01
a
S1P2
3.45±0.07
fg
7.38±0.03
a
23.85±0.07
cde
1.59±0.01
g
2.65±0.03
f
S1P3
3.35±0.07
ef
7.48±0.07
f
24.30±0.14
gh
1.05±0.01
e
2.30±0.01
e
S1P4
3.95±0.07
k
7.39±0.01
ab
24.50±0.00
hi
6.14±0.01
o
40.85±0.05
o
S2P0
3.85±0.07
jk
7.44±0.01
abcdef
23.40±0.00
a
4.47±0.01
n
3.46±0.01
gh
S2P1
3.55±0.07
gh
7.43±0.04
abcdef
23.65±0.35
abc
2.74±0.01
l
34.18±0.38
l
S2P2
3.65±0.07
hi
7.42±0.01
abcdef
23.95±0.07
def
9.70±0.02
s
35.83±0.02
m
S2P3
3.05±0.07
c
7.40±0.03
abcd
24.50±0.00
hi
6.14±0.01
o
2.25±0.01
de
S2P4
3.15±0.07
cd
7.41±0.04
abcde
24.30±0.00
gh
0.34±0.01
a
37.56±0.03
n
S3P0
2.15±0.07
a
7.40±0.00
abcd
23.45±0.07
a
7.39±0.01
p
33.75±0.01
k
S3P1
3.25±0.07
de
7.42±0.02
abcde
23.90±0.00
cdef
0.82±0.01
c
3.72±0.01
i
S3P2
3.95±0.07
k
7.39±0.03
abc
24.10±0.00
efg
1.45±0.01
f
3.28±0.04
g
S3P3
3.95±0.07
k
7.40±0.03
abcd
24.55±0.07
hi
2.05±0.01
i
3.60±0.02
hi
S3P4
3.25±0.07
de
7.42±0.01
abcde
24.15±0.07
fg
2.44±0.01
k
1.78±0.01
b
S4P0
2.65±0.07
b
7.45±0.00
cdef
23.80±0.00
bcd
2.20±0.01
j
1.84±0.01
b
S4P1
3.65±0.07
hi
7.45±0.00
cdef
23.80±0.00
bcd
0.78±0.01
b
2.09±0.01
cd
S4P2
3.25±0.07
de
7.46±0.01
def
24.10±0.00
efg
0.88±0.02
d
1.70±0.01
b
S4P3
3.55±0.07
gh
7.47±0.04
ef
24.60±0.00
i
0.76±0.01
b
2.05±0.01
c
S4P4
3.15±0.07
cd
7.44±0.01
abcdef
24.05±0.07
defg
8.55±0.01
q
1.25±0.01
a
Sig
P<0.05
P<0.05
P<0.05
P<0.05
P<0.05
Note: Means with the same superscript in the same column are not significant (P<0.05). n=2
Ammonia concentration in fish tanks varied
significantly with phytase addition to experimental
diets (P<0.05). The highest level of ammonia was
observed in tank of fish fed S2P2 (9.70±0.02mg/l),
while the lowest observed value was recorded for fish
tank fed S2P4 (0.34±0.01mg/l). Ammonia levels
increased significantly with diets based on 25%, 50%,
and 75% without phytase (P<0.05). Phytase addition
to soya bean decreased ammonia levels significantly
(Duncan, P<0.05), which also showed a significant
reduction (Tukey, P<0.05) compared to diets without
phytase, regardless of soyabean levels (Table 11).
