Milkfish Production and Processing ... - WorldFish Center

h) Apply inorganic fertilizer (16- 0-0
at 0 kg/ha or 18-46-0 at 10 kg/ha)
every weeks depending on lab-lab
growth.
• Application of fertilizer should
only be done after replacement of
pond water.
• Do not apply fertilizer during
rainy days.
• During rainy days, drain the uppermost
freshwater layer in the water
column to prevent sudden drop
in salinity.
• If fish is observed to be gasping or
swimming in circles, replenish with
new water from the river source
and if not possible draw water from
adjoining ponds. Pumps can be used
in such emergency.
• S u p p l e m e n t a l f e e d s s u c h a s
commercial fish feed, rice brand or
bread crumbs should be supplied
if lab-lab is prematurely depleted
due to overgrazing, poor water
condition, or persistent inclem-
ent weather.
i) Feed the crabs with trash fish or
mussel meat at about 10% of crab
biomass per day if crab is grown
with milkfish. Provide supplementary
feeds occasionally in the form of trash
fish, mollusks, or formulated diet to
the shrimp particularly towards the
end of the culture period if shrimps
are grown with milkfish.
j) Start selective harvest of marketable
crabs (≥ 150 g for female and ≥ 250 g
for males) after 45 to 60 days of rearing.
This is done by freshening and lift-
net methods.
k) Start harvest of milkfish when natural
food in the rearing pond becomes in
short supply and/or the target sizes
of 00 g to 500 g are attained. Use
freshening method for partial harvest
of all species being polycultured and
total drainage to harvest all the stocks
in the pond.
l) Harvest when fish are scarce in the
market to maximize profit. This is
Milkfish Production and Processing Technologies in the Philippines
usually during full moon nights when
not much fish are caught in the sea.
18.6 Semi-Intensive Pond Culture
Method
Semi-intensive culture method is characterized
by smaller pond size of 1 to 5 hectares, at
least 1 meter depth of water, and an increased
stocking rate of 8,000 to 1 ,000 fingerlings per
hectare in the rearing pond. Widening the gate,
provision of separate drain gate and using water
pump enhances water exchange. Oxygen supply
is improved by providing paddlewheel aerators
and maintaining good phytoplankton growth
later in the growing period. Natural food, mainly
lab-lab, is grown and used as food in the first
45 to 60 days of culture in the grow-out ponds
and commercial formulated diet with at least
7% protein is supplied thereafter. Production
is ,000 – ,500 kg/ha/crop. This method allows
to crops and yields of 5,000 to 7,500 kg/ha/
per year.
a) Initially follow the water and fertilization
management as outlined in Section
16.1 for the Extensive Method
b) Stocking rate is from 8,000 to 1 ,000
fingerlings per hectare with an initial
average weight of at least 60 grams
to obtain lower FCR.
c) The milkfish fingerlings to be stocked
in the grow-out module are either
reared in the farm or acquired
from commercial nurseries (cost of
producing own fingerlings and buying
outside is almost the same but regular
supply and quality are not guaranteed).
If the fingerlings come from other
source, acclimation should be done
to prevent temperature and salinity
shock as follows:
• If salinity and temperature of transport
containers and nursery pond
are approximately the same, stock
the fish directly.
• If not let the transport containers
float in the nursery pond for 15 to
0 minutes to equalize the temperature
of the containers with the
pond water.
• If salinity difference between transport
containers and nursery pond
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