ESTUARINE FISH FARMINU
193
they need little attention so long as abundant food is present, except
for the frequent renewal of the water. But should this natural food
become exhausted, other foods such as digman (several species of
Hydrocharitaceae) or gulaman dagat, (Gracilaria sp.) may be given.
Mane et al. (1952) state that each pond system includes a catching
pond, about 20-30m square, and in this the marketable fish are
collected for sale when the ponds are drained.
Blanco and Acosta (1958) describe a rural-industrial farming of grey
mullet and other fish in Luzon, in small brackish-water enclosures of
about $ hectare area, fitted with wooden or bamboo gates. These
ponds are stocked haphazardly, as are those of the Indian bheris, by
opening the gates on the rising tides and closing them when the tide
falls. The fish are held in these ponds for 6-8 months and then used or
sold. The fish chiefly depend on the natural food available in the pond
but supplementary food may be given. Grey mullet, which are among
the most important of the fish reared in these ponds, grow fast on these
foods. Blanco and Acosta point out that at this subsistence level,
operational expenses for the ponds are very low.
K. Fishpond management in Japan
Accounts of fishpond management in Japan are hard to come by,
but, in their article, Blanco and Acosta (1958) briefly describe the culture of grey mullet in Japan. I n March and April, young Mugil cephalus
about 3-6 cm long, swarm in the estuaries of the rivers, where they are
caught and transplanted to rearing ponds in brackish water or salt
fields. The rate of stocking is 1-3 individuals per m2. The fish grow
to a commercial size of 200g by the end of October or November.
The Japanese fish farmers do not grow the grey mullet alone, but together with carp or eels or both, in the same pond, and sharing the same
foods such as rice bran and flour. This is confirmed in Asia Kyokai
(1957) where it is stated that the young grey mullet migrating up the
rivers are caught and placed in ponds where they are grown together
with other fish, chiefly eels. This culture takes place in brackish, more
frequently than in fresh water. No artificial foods are given to the grey
mullets, which feed on the residues of foods given to the other fish.
There is no need to doubt that these grey mullet would be feeding on
bottom soil enriched by the faeces and food fragments left by the other
fish.
The writer saw the culture of eels in Taiwan, but this time in a
fresh-water pond. The fish were fed on trash fish bought from the fish
market in Taipeh, the capital, for 2 local dollars per kg (Fig. 14). The
conversion ratio was said to be about 13 t o 1, so that crude costs per
193
they need little attention so long as abundant food is present, except
for the frequent renewal of the water. But should this natural food
become exhausted, other foods such as digman (several species of
Hydrocharitaceae) or gulaman dagat, (Gracilaria sp.) may be given.
Mane et al. (1952) state that each pond system includes a catching
pond, about 20-30m square, and in this the marketable fish are
collected for sale when the ponds are drained.
Blanco and Acosta (1958) describe a rural-industrial farming of grey
mullet and other fish in Luzon, in small brackish-water enclosures of
about $ hectare area, fitted with wooden or bamboo gates. These
ponds are stocked haphazardly, as are those of the Indian bheris, by
opening the gates on the rising tides and closing them when the tide
falls. The fish are held in these ponds for 6-8 months and then used or
sold. The fish chiefly depend on the natural food available in the pond
but supplementary food may be given. Grey mullet, which are among
the most important of the fish reared in these ponds, grow fast on these
foods. Blanco and Acosta point out that at this subsistence level,
operational expenses for the ponds are very low.
K. Fishpond management in Japan
Accounts of fishpond management in Japan are hard to come by,
but, in their article, Blanco and Acosta (1958) briefly describe the culture of grey mullet in Japan. I n March and April, young Mugil cephalus
about 3-6 cm long, swarm in the estuaries of the rivers, where they are
caught and transplanted to rearing ponds in brackish water or salt
fields. The rate of stocking is 1-3 individuals per m2. The fish grow
to a commercial size of 200g by the end of October or November.
The Japanese fish farmers do not grow the grey mullet alone, but together with carp or eels or both, in the same pond, and sharing the same
foods such as rice bran and flour. This is confirmed in Asia Kyokai
(1957) where it is stated that the young grey mullet migrating up the
rivers are caught and placed in ponds where they are grown together
with other fish, chiefly eels. This culture takes place in brackish, more
frequently than in fresh water. No artificial foods are given to the grey
mullets, which feed on the residues of foods given to the other fish.
There is no need to doubt that these grey mullet would be feeding on
bottom soil enriched by the faeces and food fragments left by the other
fish.
The writer saw the culture of eels in Taiwan, but this time in a
fresh-water pond. The fish were fed on trash fish bought from the fish
market in Taipeh, the capital, for 2 local dollars per kg (Fig. 14). The
conversion ratio was said to be about 13 t o 1, so that crude costs per