274
K. Opuszyñsä
A
«=
Better utilization of natural too—d
Better
utilization of natural food is most frequently cited as on
obvious
advantage of
This
is
based
on
the
assumption
that
carp°
in spite of its wide food rangeg does not fuliy utilize all
food
ln
general,, when the food habits of fish species se—
lected
for
potyculture ore distinct, the competition for food is reduced
and
the
potential for increased total fish production is
For
this
reason
the
most
profitable results are obtained in corp culture
together
with herbivorous and detrivorous fish
(Simba. and Olâho
Mutuel food
relations between fish species9 however,mîght be
very complex, Sometimes on interspecific competition is asymetric as
was
found
by Yashouv (1972) in the many years of experiments of
the
combined growth of corp with tilapio° Tiiapia affected the growth
of
the
corp
only when tilopia were at a large
and
even
than,
the
effect
was
only slighh The carp,, however,coused the growth
of
the
tilapia to decrease
Many data have been collected
rea—
cently that indicate fish species can abandon their normal behaviour
of
feeding within fixed trophic niches in densly stocked ponds
1980)‘ For example,, corp which is commonly considered
as
a
benthos
feeder
con
shift under such
conditions
to
detritus,,
and
even
to
plant food (Opuszäyñski, 1969; Sandhu and Toor9 1983).
When
a
dense
stock
of
corp is
raised in monoculture
a
moss
scale
development of small crustacean,, Bosmina Iongirostris,
takes
place… This phenomenon should be looked upon as a harmful side
effect
of intensified corp production. B., longirostrisa which is consumed
by corp only to a very small extent, feeds on phytoplankton which
serves
for“
a
staple food of other animal organisme signicant in the
corp
diet. Silver corp raised together with corp feeds readily
on
B.
longirostris (Opuszyñski,,
This
seems
to
be
of
double
In
addition to a better utilization
of food
resources
for
fish
productiom it has a restrictive effect on the numerical increase
of
this
crustaceam
B
«=
Enhancement of natural food
The
synergistic interaction between corp and silver corp
is
possible because of the activity of each species which increases
food
sources
available
to
the
other
(Yashouv, 1971; Spatoru, 1977)»
The
focal
pellets of the silver corp, which are rich in
partially
digested phytopianktom make this food source available to the corp
which
otherwise
could
not utilize
the
phytop1ankton, The common corp
in
turn» bY Shining up the
releases into
the
water
detritus
particles which are then utilized by the silver
In
addition&
Asiatic
planktivorous fish can exert considerable effects on algae in
pondsu In the ponds stocked with silver corp or bighead there were
changes in the structure of the algae communities and a twofold
increase
in
algal biomass was obserwed in comparison to the con—=trol
ponds stocked with corp alone
(_Jonuszkog 1978).
C
-—
…
Raising additional fish species in corp ponds brings about
a
number
of
physico—chemical olternations in the ecosysterm The impact
of
silver
corp
was
studied
carefuly (Wolnye 1970;
Piotrowska
-—
GPU“
K. Opuszyñsä
A
«=
Better utilization of natural too—d
Better
utilization of natural food is most frequently cited as on
obvious
advantage of
This
is
based
on
the
assumption
that
carp°
in spite of its wide food rangeg does not fuliy utilize all
food
ln
general,, when the food habits of fish species se—
lected
for
potyculture ore distinct, the competition for food is reduced
and
the
potential for increased total fish production is
For
this
reason
the
most
profitable results are obtained in corp culture
together
with herbivorous and detrivorous fish
(Simba. and Olâho
Mutuel food
relations between fish species9 however,mîght be
very complex, Sometimes on interspecific competition is asymetric as
was
found
by Yashouv (1972) in the many years of experiments of
the
combined growth of corp with tilapio° Tiiapia affected the growth
of
the
corp
only when tilopia were at a large
and
even
than,
the
effect
was
only slighh The carp,, however,coused the growth
of
the
tilapia to decrease
Many data have been collected
rea—
cently that indicate fish species can abandon their normal behaviour
of
feeding within fixed trophic niches in densly stocked ponds
1980)‘ For example,, corp which is commonly considered
as
a
benthos
feeder
con
shift under such
conditions
to
detritus,,
and
even
to
plant food (Opuszäyñski, 1969; Sandhu and Toor9 1983).
When
a
dense
stock
of
corp is
raised in monoculture
a
moss
scale
development of small crustacean,, Bosmina Iongirostris,
takes
place… This phenomenon should be looked upon as a harmful side
effect
of intensified corp production. B., longirostrisa which is consumed
by corp only to a very small extent, feeds on phytoplankton which
serves
for“
a
staple food of other animal organisme signicant in the
corp
diet. Silver corp raised together with corp feeds readily
on
B.
longirostris (Opuszyñski,,
This
seems
to
be
of
double
In
addition to a better utilization
of food
resources
for
fish
productiom it has a restrictive effect on the numerical increase
of
this
crustaceam
B
«=
Enhancement of natural food
The
synergistic interaction between corp and silver corp
is
possible because of the activity of each species which increases
food
sources
available
to
the
other
(Yashouv, 1971; Spatoru, 1977)»
The
focal
pellets of the silver corp, which are rich in
partially
digested phytopianktom make this food source available to the corp
which
otherwise
could
not utilize
the
phytop1ankton, The common corp
in
turn» bY Shining up the
releases into
the
water
detritus
particles which are then utilized by the silver
In
addition&
Asiatic
planktivorous fish can exert considerable effects on algae in
pondsu In the ponds stocked with silver corp or bighead there were
changes in the structure of the algae communities and a twofold
increase
in
algal biomass was obserwed in comparison to the con—=trol
ponds stocked with corp alone
(_Jonuszkog 1978).
C
-—
…
Raising additional fish species in corp ponds brings about
a
number
of
physico—chemical olternations in the ecosysterm The impact
of
silver
corp
was
studied
carefuly (Wolnye 1970;
Piotrowska
-—
GPU“