International Journal of Aquaculture, 2013, Vol.3, No.16, 85
-
91
http://ija.sophiapublisher.com
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Table 5 Ranges of water quality parameters observed during the
course of experiment
Parameters
Range
DO
2.6
-
3.8
mg/L
Temp
24
-
30
℃
E.C
1.27
-
2.10
µS/cm
TDS
978
-
1150
mg/L
Salinity
0.7
-
0.9
mg/L
pH
6.97
-
8.43
catla
was fed on soybean meal (Table 1) or when
Cirrhinus mrigala
was fed on cotton seed meal. Growth
comparison of
Catla catla
showed significantly higher
growth when fed on soybean meal followed by rice
polish and cotton seed meal.
Hypophthalmichthys
molitrix
grew significantly less than its counterparts
(
Table 1). Findings of Yasmin (1987) support and
confirm our findings who reported better performance
of
Cirrhina mrigala
than
Lobeo rohita
and
Catla
catla
in artificial feed supplemented pond. Our observations
are quite in line with previous investigations because
Cirrhinus mrigala
elicited superior growth performance
on all the feed ingredients than its counterparts.
Findings of Ashraf et al. (2008) further verify our
investigations who observed different growth
responses when
Cirrhinus mrigala
fingerlings were
fed on different feed ingredients.
Hypothalmicthis
molitrix
generally showed poor growth in all the
ingredients nevertheless it was selectively comparable
with
Cirrhinus mrigala
when it was fed on soybean
meal or with
Catla catla
when it was fed on cotton
seed meal.
The nature and composition of the diet administered
strongly triggers the development and secretion of
digestive enzymes which affects the metabolic
capabilities of fish. These enzymes had been an
effective tool for identification of particular
components of animal’s diet (Kanou et al. 2000).
When sea bream specimens were fed on protein rich
and non-proteic diets, it reflected type of diet in the
secretion of gut enzymes. Protein rich diets resulted in
higher amounts of proteases while amylase and lipase
levels were greater in fish fed low protein diets. Fish
may adapt their metabolic functions to the dietary
substrates, through a regulation in enzyme secretion,
in order to improve the utilization of particular feed
ingredients (Caruso et al
.
, 2009).
Results were quite
interesting in current studies where all the enzymes
studied viz. amylases, lipases and proteases differed in
different species and when fed on different ingredients
(
Table 2, Table 3, and Table 4). These findings
strongly suggest that secretions of intestinal enzymes
are dependent both on fish species and type of diet.
This emphasizes that there are dietary as well as
anatomical adaptations in fish. Fernandez et al. (2001)
pointed out that digestive adaptations in different
species exhibit closer correlation with their diet rather
than on their taxonomic category. Our studies support
former part of their findings but contradict the later
part further confirming that taxonomical differences
do have bearing on digestive adaptations in fish. This
view was also confirmed by the results of Kuzmina
(1996
a) who indicated that changes in digestive
enzyme activity could be affected by feeding behavior
and biochemical composition of feed. Chan et al.
(2004)
and German et al. (2004) investigated the
digestive enzyme activities in four closely related
prickle back fishes, including two herbivorous and
two carnivorous species. Their results showed that the
activities of digestive enzymes correlated more
strongly with phylogeny rather than with the fish’s
natural diets. Influence of the genetic strains on the
activities of brush border enzymes was demonstrated
in the crosses of
Oreochromis mossambicus
and
O
.
aureus
(
Hakim et al., 2006) and in the silver perch
Bidyanus bidyanus
(
Hakim et al., 2006). Furthermore,
the activities of digestive enzymes were also
influenced by many other factors such as the ages of
the fishes (Kuzmina, 1996), temperature and season
(
Kuzmina et al., 1996b) and the composition of their
diets (Zambonino Infante and Cahu, 2001).
Significantly higher amylases were observed in
Cirrhinus mrigala
when fed on rice polish and
soybean meal, higher lipase levels were evident in
Catla catla
and similarly variable proteases were
present in different species when fed on different feed
ingredients. Chaudhuri et al. (2012) measured
enzymes (i.e. α-amylase, invertase, cellulose, alkaline
protease and pepsin) from liver, stomach and intestine
of ten carnivorous species and did not find any
positive relationship between prey preferences and
digestive enzymes. These studies further strength ours
and suggest that enzyme patterns are more affected by
phylogeny rather than adaptability. The findings of
Essa et al. (2010) further support our view point who
observed that Tilapia fed on diets containing different