Milkfish Production and Processing ... - WorldFish Center

Antonio Villaluz
Figure 1 . Typical layout of traditional milkfish farm.
5 fingerlings per m for further growing to
post-fingerlings. Stocking density of milkfish
fingerlings or post-fingerlings in the rearing
pond ranges from 1,000 to ,000 per hectare
depending on the availability of natural food in
the pond and the target size at harvest ( 00 to
500g per fish). Harvesting of the fish is usually
done at one time. Milkfish production for this
method varied from 00 to 900 kg per hectare
per crop or an annual production of 600 kg to
1,800 kg per hectare.
The growing of the milkfish follows the following
procedure:
a) The rearing pond should be prepared
1 to 1½ months ahead of stocking
fingerlings.
b) Follow pond preparation proce-
dures indicated in Section 13 but
installation of artificial net substrate
is omitted.
c) Stocking rate is from 1,000 to ,000
per hectare depending on the availability
of natural food in the pond and
the target size at harvest ( 00 to 500g
per fish).
d) Maintain water depth at 0 to 40 cm.
Recommended mesh size for gate
screen is 1.5 cm.
e) Replace one half to one third of pond
water every spring tide. Care should
be taken in draining and flooding of
the grow-out pond as not to detach
the lab-lab from the pond bottom.
Milkfish Production and Processing Technologies in the Philippines
f) Environmental factors affecting
growth and survival of milkfish in the
pond are as follows:
• Dissolved oxygen – optimum level is
-10 ppm, below this level is harmful
to the fish; during sudden rains, drain
water from the surface or admit
water to prevent sudden drop in
salinity and temperature; during
summer, closely monitor the water
level and admit water frequently.
When fish are observed gasping at
the surface or swimming in circles,
replenish with new water and if not
possible draw water from adjoining
ponds. Pumps can be used in such
emergency.
• Weather conditions – sudden change
in weather condition causes oxygen
depletion in ponds:
• During sudden rains, drain water
from the surface or admit water to
prevent sudden drop in salinity and
temperature;
• During summer, closely monitor
the water level and admit water
frequently.
• When fish are observed gasping at
the surface or swimming in circles,
replenish the water to agitate the
pond water.
• Salinity – milkfish growth is retarded
at 45 ppt salinity; frequent water
exchange should be done during the
summer months.
• Water temperature – affects metabolism
of fish and consequently
growth rates; optimum tempera-ture
is 5- °C; growth is reduced at
°C.
• pH – indicates the presence of
metabolites, photosynthetic activity
and fertility of pond water; high pH
value indicates that the pond water
is too fertile, therefore, there is a
possibility of a plankton bloom; low
pH means the water is infertile and
plankton growth is slow; optimum
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