1
96
Aquaculture of Cyprinids
1
The
timing, amplitude and velocity of mouth Opening, protrusion of the upper ‘
jaws, opening of the opercular valves and the volume changes in the oral,
«
buccal, pharyngeal and opercular cavities determine the effects of each
single pattern on the food. The archtecture and activity patterns of the
;
head determine the specializations for certain food types and the consequent
restrictions for others. The feeding apparatus of the carp appears to be
specialized to process medium—sized and hard food particles (eg. seeds and
shelled mollusks) from 250pm.to 3—42 of its standard body length, even when
these are mixed with unedible bottommaterial. This "ominivorous" fish is
however also limited by its specializations in the exploitation of the
available food sources. Large, fast or struggling prey as well as large and
flat plant material can hardly be utilized by the carp. By comparing fish
species in this way insight in their trophic interrelations and coumetition
for food can be greatly improved.
Concludmg remarks
1
.
1
1
The nutritional requirements of carp differ little from those establiœd
for Carnivorous fish, despite the particularities of their digestive tract :
1
absence of
stomach and a long intestine. Thus when these figures are expres—
sed in absolute terms, i.e.
as
quantity of intake per day, the protein needs
are
similar to those of other fish. A protein—sparing action of lipids has
also been noted. Likewise, when adequate experimental diets and feeding frequencies are used, the amino acid needs are also comparable to those reported
of other species (Wilson, 1985).
On the contrary, as regards the essential fatty acid requirements, it
is
worth mentioning the superiority of a mixture of n—3 and n—6 series of
ty ac1ds compared to the use of n—3 series fatty acids alone. Like in the case
of the well—known effect of salinity on long chain fatty acid requirements,
the question
arises as to the specific effects of high temperatures on the
requirements
of n—6_series of fatty acids, these having been recognized as
indispensable for Tilapia (Kanazawa, 1985). Little research has been under—
tahen on warm water fish or fish grown in high temperatures and questions
ar1se,
on
the specific nature of requirements or of the formulations capable
of
sat13fying such needs at higher temperatures.
The satisfaction of vit B12 requirement is exemplary in this connectionAs reported by Dabrowski in this review, the intestinal microflora of carp
and
catfish
is capable of synthesizing this vitamin. The nature of this microflora
1s
similar
to
that of the environment in which the fish live (Lesel, 1981)
and in the ponds, bacterial flora is often found at densities equivalent to
that found in fish (106/m1 hence per g) (Rheinhäimer, 1980). Among these,
about 50 % have been recognized as being capable of vit B12 synthesis and
among them, two strains are capable of producing 0.16 mg vit BIZ/ml in 3 days
(N1ewolak and Sobierajska, 1971). To these latter authors'question on the
consequences of this production of vitamins on pond productivity, Kovalsky
(1979)
has positive answers: fertilization of ponds with Cobalt increases
cons1derably
the vitamin
B12
concentration at each trophic level including
fish whose biomass can even be doubled, if simultaneously there is an increa*
SEd supply of
ammonium nitrate and superphosphate through fertilization. This
example
of vitamÈ1B12 supply is only one of the many characteristic ones, as
s1gn1f1cant increases in cabalamines, biotine or niacine through rainwater
have been reported by Parker and Wachtel (1970). Therefore, besides the supply
of
those nutrients having a role of fertilizaters (N, P, K) though water
96
Aquaculture of Cyprinids
1
The
timing, amplitude and velocity of mouth Opening, protrusion of the upper ‘
jaws, opening of the opercular valves and the volume changes in the oral,
«
buccal, pharyngeal and opercular cavities determine the effects of each
single pattern on the food. The archtecture and activity patterns of the
;
head determine the specializations for certain food types and the consequent
restrictions for others. The feeding apparatus of the carp appears to be
specialized to process medium—sized and hard food particles (eg. seeds and
shelled mollusks) from 250pm.to 3—42 of its standard body length, even when
these are mixed with unedible bottommaterial. This "ominivorous" fish is
however also limited by its specializations in the exploitation of the
available food sources. Large, fast or struggling prey as well as large and
flat plant material can hardly be utilized by the carp. By comparing fish
species in this way insight in their trophic interrelations and coumetition
for food can be greatly improved.
Concludmg remarks
1
.
1
1
The nutritional requirements of carp differ little from those establiœd
for Carnivorous fish, despite the particularities of their digestive tract :
1
absence of
stomach and a long intestine. Thus when these figures are expres—
sed in absolute terms, i.e.
as
quantity of intake per day, the protein needs
are
similar to those of other fish. A protein—sparing action of lipids has
also been noted. Likewise, when adequate experimental diets and feeding frequencies are used, the amino acid needs are also comparable to those reported
of other species (Wilson, 1985).
On the contrary, as regards the essential fatty acid requirements, it
is
worth mentioning the superiority of a mixture of n—3 and n—6 series of
ty ac1ds compared to the use of n—3 series fatty acids alone. Like in the case
of the well—known effect of salinity on long chain fatty acid requirements,
the question
arises as to the specific effects of high temperatures on the
requirements
of n—6_series of fatty acids, these having been recognized as
indispensable for Tilapia (Kanazawa, 1985). Little research has been under—
tahen on warm water fish or fish grown in high temperatures and questions
ar1se,
on
the specific nature of requirements or of the formulations capable
of
sat13fying such needs at higher temperatures.
The satisfaction of vit B12 requirement is exemplary in this connectionAs reported by Dabrowski in this review, the intestinal microflora of carp
and
catfish
is capable of synthesizing this vitamin. The nature of this microflora
1s
similar
to
that of the environment in which the fish live (Lesel, 1981)
and in the ponds, bacterial flora is often found at densities equivalent to
that found in fish (106/m1 hence per g) (Rheinhäimer, 1980). Among these,
about 50 % have been recognized as being capable of vit B12 synthesis and
among them, two strains are capable of producing 0.16 mg vit BIZ/ml in 3 days
(N1ewolak and Sobierajska, 1971). To these latter authors'question on the
consequences of this production of vitamins on pond productivity, Kovalsky
(1979)
has positive answers: fertilization of ponds with Cobalt increases
cons1derably
the vitamin
B12
concentration at each trophic level including
fish whose biomass can even be doubled, if simultaneously there is an increa*
SEd supply of
ammonium nitrate and superphosphate through fertilization. This
example
of vitamÈ1B12 supply is only one of the many characteristic ones, as
s1gn1f1cant increases in cabalamines, biotine or niacine through rainwater
have been reported by Parker and Wachtel (1970). Therefore, besides the supply
of
those nutrients having a role of fertilizaters (N, P, K) though water