216
S.J. Kaushik
ln
recent
years,
considerable
advances
have
been
accomplished
in
the
rearing of fish larvae with artificial
diets
right
from
the
first
feeding onwards
(Dabrowski et al. 1984; Bergot
et
al.
1985;
Dabrowski
et
al.
1985).
This
success
is
attributable
both
to
judiÉÏouË_dietary formulations and
to
adequate
rearing
technologies
(Charlon
and
Bergot
1984;
Bergot et al.
1985).
The
particularities inherent to larval
feeding—practices were reviewed in detail by Dabrowski (1984)
and
he
pointed out also the difficulties encountered in
the
estimation
of
nutrient
requirements of larval
and
juvenie
fish.
Since
a
number
of
morphological and functional changes
take
place
during
early
development,
an
appraisal
of
basic
metabolic
activities
during early ontogenesis should
provide
us
fundamental
data
from which
few
generalizations as regards
the
nutritional
specificities could be
drawn.
This
paper
tries
to
present
some
of
the
observations
drawn
from
metabolic
data
obtained
during ontogenesis and early life of
Carp,
Cyprinus Carpio,
over
the
past few years.
Comparative
data
from
other
species
are
also
presented
whenever
appropriate.
Broodstock
nutrition ys Êgg quality
Although
in
many
species
of
fish,
the
qualitative
and
quantitative
differences
in
the
endogenous reserves in
the
eggs
of
the
progeny
are
known
to
be
affected
by
the
nutritional
status
of
the
spawners
(Luquet
and
Watanabe
1985),
little
work
has
been
devoted
to
this
interaction
between
nutrition
and
reproduction in Cyprinids
(Zhukinsky
and
Nedyakov 1980).
Horvath
(1978)
showed
that
depending
on
the
energy
content
of
the
diet,
the
response
to
hypophysation
differed
in
the
Carp.
A
high
lipid
diet
accelerated
vitellogenesis
but
subsequent feeding with
the
same
diet
beyond
this
stage
had
detrimental
effects.
Sexspecific
differences
also
seem
to
exist.
The
gonadosomatic index was
found
to
be
inversey related to the dietary fat
content
in
the
female
Carp,
whereas
in
the
male
a
positive relationship
was
observed
(Hilge 1979).
Utilization of Endogenous Reserves
Among
the
different
energy—yielding
substrates
(lipids,
glycogen,
free
glucose,
free
amino
acids
or
adenyate
nucleotides)
available
for
the
maturing
teleosteen
eggs,
protein
and
fats
were
found to be
equal
contributors
of
energy
in
Cyprinus
Carpio
(Kamler
1976).
Continuous
measurements
of
nitrogen—_Ëxcretion and
of
oxygen
uptake
during ontogenetic
of
Carp were made by Kaushik et
al.
(1982).
Based
on
these
simple parameters,
they estimated
that
the
ratio of
fat
to
protein utilized
by
Common
Carp
amounted
to
1.9,
5.0
and
4.0
before
hatching,
during
stationary larval and free—swimming stages respectively.