Milkfish Production and Processing ... - WorldFish Center

the nurseries to the culture pens.
Delivery of seeds is done in calm
days as a preventative measure to
minimize stress.
• If the fingerlings are transported
using live-fish boat, gradual acclimation
to pen environment is
undertaken during transport.
- Acclimation is done by pumping
out partially at interval the
original water from the source
of fingerlings. Simultaneous
with this is the removal of a
hole plug in the boat to allow
water from the lake, river, or
sea to come in;
- As soon as fish pen is reached,
the fingerlings are seined out
and transferred carefully into
the pen nursery.
b) If the fingerlings are transported
using oxygenated plastic bags, the
following acclimation procedures
should be made to prevent temperature
and salinity shock.
• Let the plastic transport containers
float in the nursery pen for
15 to 0 minutes to equalize the
temperature of the containers
with the surrounding water.
• If salinity difference between
transport containers and nursery
pen is above 5 ppt, gradually add
pen water to transport containers
until salinity is equalized
before releasing the fingerlings.
• Allow the fingerlings to swim
out of the containers into the
pen nursery.
c) While in the pen nursery the fingerlings,
depending on the abundance
of natural food, should be fed with
fine rice bran or commercial feed
pellets at about to 5 percent of
the extrapolated fish biomass.
d) Control of predators in the nursery
compartment is done using peated
netting.
Milkfish Production and Processing Technologies in the Philippines
e) The stocks stay in the nursery for
one to two months depending on
the desired grow-out stocking size
or until such time that it is no longer
possible for them to pass through
the grow-out net enclosure.
23.4.2 Fish Pen Grow-out
a) Elimination of predators and competitors
in the grow-out compartment
should be undertaken using
peated netting before stocking.
b) Fingerlings are released to the growout
compartment by lowering one
side of the nursery net.
c) The main cause why the growth
potential of appropriately fed fish
is not fully achieved is that stocking
density has exceeded the carrying
capacity of the system. An optimum
density and proper feeding are
required for economical fish pen
operation.
d) Stocking rates depends on the location
of the pens and abundance of
natural food.
• Laguna de Bay – 3 to 5 fish per m
• Marine and brackishwater
environments – 6 to 1
fingerlings per m
e) No feeding or just supplementary
feeding is required in pens located
in areas with abundant natural
food such as Laguna de Bay but in
areas with insufficient natural food
(marine and brackishwater) and high
stocking densities feeding of high
protein formulated diet ( 7- 1%
protein) is essential.
f) Commercial formulated pellets are
expensive and, therefore, good feeding
practice should be followed to
obtain fast growth rate of fish, low
feed conversion and at the same
time prevent pollution of water and
deterioration of the pen bottom.
g) Training of the milkfish to feed on
artificial diet is necessary for
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