Worldwide siaî‘us of carp culture
29
dense
rotifer
cultures
by
application
of
arthropod—specific
organophosphate
pesticides has revolutionized postlarval production in many hatcheries (May et al.,
1984; Jhingran and Pullin, 1985). Some hateheries may move towards utilization of
complete dry diets,
but
many still prefer live foods°
Moreover, Lubzens
et
al.
(1984) have shown
that Brachi0nus plicatis, the mainstay
of saltwater hatchery
production, can be used for carps. It reproduces in salinities from 2 to 40 ppt and
individuals kept at lOppt survive for over 24 hr in freshwater.
Carp nutrition has
been comprehensively reviewed by Jauncey (1982), but a
'carp equivalent'
of the
tilapia practical feeding guide
(Jauncey
and
Ross, 1982) for use with
feedstuff
composition tables (NRC, 1983) is also needed.
The common
carp is an excellent
experimental fish
and has been used in many basic nutritional studies.
It requires
about 31 % dietary protein (Takeuchi et al.,
1979).
Supplemental pellets for ponds
can
incorporate lower levels (25%) whereas
complete feeds for cage
culture
in
clear
water need
more
(e…g., in
Korea,
40%.
for
fingerlings, 3674 for growout)…
Carp
have
gut bacteria, which can be affected
by some feeding practices
(e.g.
Hubbert, 1983).
Common
carp can
utilize
cheap feedstuffs. Ufodike and
Matty
(1983) found that fingerlings (4.0—4.3g) grew well on high carbohydrate feeds; e.g.,
45%
rice (in 287°
protein
feed).
Viola
et
al.,
(1981—82)
introduced oil—coated
pellets,
since adopted by
Israeli feed mille.
Hepher
and
Sandbank (1984) have
shown that phosphorus
supplementation of carp feeds can
be beneficial, probably
because
there is
insufficient
available phosphorus
in
natural
feeds
for
large
standing crops of fish.
Future research
will likely address: l., digestive physiology
and 2.
feed
formulations
for more cost—efficient conversion.
The
main limiting
factor
in feed
formulation (other than costs)
is
probably
the effects of energy
sources
on
carcass
composition.
Increasing feed
energy
content
can
increase
carcass
fat (eg. Zeitler et al., 1984).
D — Culture systems
In
Asia”, Chinese—ster concrete circular spawning/rearimg
tanks
are
widely
used because of low cost and large capacity. Glass jars and other small incubation
units
are
less
used,
despite
their higher standards of
hygiene.
A new
Asian
development
is
the
'Dwidevi'
polyethylene
rearing
system
(Dwidevi
and
Ravindranathan,
1982) but
it is
too early
to
see
whether
this will be widely
adopted.
In
many
deve10ping
c0untries, traditional
methods
persist, including
rice—field seed production.
For
growout
systems, little is
new
but the
trend is
more
intensification, especially cage culture.
In
Chinese
polyculture, the
grass
carp
eats
supplemental vegetation; the
bighead crops zooplankton; the silver
carp filter - feeds in the water column; the
mud carp and common carp eat benthos/detritus and the
black carp eats molluscs.
In Indian 'composite' fish culture, the
major carps are
cultured together or with
one
or
more
or
all of the
Chinese carpe and/or common carp.
In
Israel, common
carp, silver
carp, mullets and tilapias are grown together alth0ugh the trend is to
separate tilapias
from
such polycultures.
All these polycultures
give impressive
yields, but Optimization is difficult. The feeding niches of some component species
are
not
well separated.
Moreover most works
on
polyculture and on the concepts
of
balance
and competition
between
species
and
their
foods
lack
economic
analyses.
Increased production
does not
always mean
increased profitabüity or
even
significant nutritional benefits if demand for the product is low.
Polyculture therefore merits reappraisal on biological and
economic grounds.
Will Chinese and
Indian p0‘lyculture have a
long—term future as scarcity of water
and land resources forces intensification?
Is it necessary to use so many species?
29
dense
rotifer
cultures
by
application
of
arthropod—specific
organophosphate
pesticides has revolutionized postlarval production in many hatcheries (May et al.,
1984; Jhingran and Pullin, 1985). Some hateheries may move towards utilization of
complete dry diets,
but
many still prefer live foods°
Moreover, Lubzens
et
al.
(1984) have shown
that Brachi0nus plicatis, the mainstay
of saltwater hatchery
production, can be used for carps. It reproduces in salinities from 2 to 40 ppt and
individuals kept at lOppt survive for over 24 hr in freshwater.
Carp nutrition has
been comprehensively reviewed by Jauncey (1982), but a
'carp equivalent'
of the
tilapia practical feeding guide
(Jauncey
and
Ross, 1982) for use with
feedstuff
composition tables (NRC, 1983) is also needed.
The common
carp is an excellent
experimental fish
and has been used in many basic nutritional studies.
It requires
about 31 % dietary protein (Takeuchi et al.,
1979).
Supplemental pellets for ponds
can
incorporate lower levels (25%) whereas
complete feeds for cage
culture
in
clear
water need
more
(e…g., in
Korea,
40%.
for
fingerlings, 3674 for growout)…
Carp
have
gut bacteria, which can be affected
by some feeding practices
(e.g.
Hubbert, 1983).
Common
carp can
utilize
cheap feedstuffs. Ufodike and
Matty
(1983) found that fingerlings (4.0—4.3g) grew well on high carbohydrate feeds; e.g.,
45%
rice (in 287°
protein
feed).
Viola
et
al.,
(1981—82)
introduced oil—coated
pellets,
since adopted by
Israeli feed mille.
Hepher
and
Sandbank (1984) have
shown that phosphorus
supplementation of carp feeds can
be beneficial, probably
because
there is
insufficient
available phosphorus
in
natural
feeds
for
large
standing crops of fish.
Future research
will likely address: l., digestive physiology
and 2.
feed
formulations
for more cost—efficient conversion.
The
main limiting
factor
in feed
formulation (other than costs)
is
probably
the effects of energy
sources
on
carcass
composition.
Increasing feed
energy
content
can
increase
carcass
fat (eg. Zeitler et al., 1984).
D — Culture systems
In
Asia”, Chinese—ster concrete circular spawning/rearimg
tanks
are
widely
used because of low cost and large capacity. Glass jars and other small incubation
units
are
less
used,
despite
their higher standards of
hygiene.
A new
Asian
development
is
the
'Dwidevi'
polyethylene
rearing
system
(Dwidevi
and
Ravindranathan,
1982) but
it is
too early
to
see
whether
this will be widely
adopted.
In
many
deve10ping
c0untries, traditional
methods
persist, including
rice—field seed production.
For
growout
systems, little is
new
but the
trend is
more
intensification, especially cage culture.
In
Chinese
polyculture, the
grass
carp
eats
supplemental vegetation; the
bighead crops zooplankton; the silver
carp filter - feeds in the water column; the
mud carp and common carp eat benthos/detritus and the
black carp eats molluscs.
In Indian 'composite' fish culture, the
major carps are
cultured together or with
one
or
more
or
all of the
Chinese carpe and/or common carp.
In
Israel, common
carp, silver
carp, mullets and tilapias are grown together alth0ugh the trend is to
separate tilapias
from
such polycultures.
All these polycultures
give impressive
yields, but Optimization is difficult. The feeding niches of some component species
are
not
well separated.
Moreover most works
on
polyculture and on the concepts
of
balance
and competition
between
species
and
their
foods
lack
economic
analyses.
Increased production
does not
always mean
increased profitabüity or
even
significant nutritional benefits if demand for the product is low.
Polyculture therefore merits reappraisal on biological and
economic grounds.
Will Chinese and
Indian p0‘lyculture have a
long—term future as scarcity of water
and land resources forces intensification?
Is it necessary to use so many species?