ESTUARINE FISH FARMINQ
179
ance of the salt marsh, from which they were made, by the end of the
war.
Though conditions had prevented any of the usual measures of
pond maintenance, the Tilapia found suitable conditions, so that they
gave rise t o a productive fishery, chiefly with cast nets a t monthly
intervals. Nevertheless, the pond soil showed no sign of exhaustion,
the production of blue-greens and diatoms was abundant. The
green algae which also flourished were kept in check by the Tilapia,
which thus also helped to solve a health problem, for malarial mosquitoes bred dangerously among the floating masses of green algae.
Schuster found that, in brackish water, Tilapia could grow t o a
weight of a pound or more in eight months-a far better performance
than in fresh water ; but commercially the best results were obtained
by marketing at about 3-5 ounces weight, which would be at lengths
of about 17-22 cm.
It proved possible, in fertile shore ponds, t o cultivate prawns and
Tilapia together, the Tilapia breeding naturally, and the prawns
entering the ponds as larvae with the filling water. Schuster quotes
statistics of the fishpond system, " Heemrad ", near Djakarta where,
in 1947-8, prawns were produced a t the rate of 60-85 lb per acre per
annum, as well as 170-260 lb of Tilapia.
Tilapia has established itself in the Singapore prawn ponds, and
some reasonably well-grown specimens (up to 270g in weight) can
be found when required. Le Mare (1950) showed convincingly the value
of T . mossambica as a fish for brackish-water fish culture. He empoldered an area of saline swamp in Singapore, on which were eight
Malay houses, built, as is customary, on stilts over the water, and
therefore whose household wastes fertilized the area. No other fertilizer
was used, and the salinity was maintained at 20%,. The shrimp
Acetes, penaeid prawns, and fish, especially grey mullet, entered the
pond with the water, and the filled pond was stocked with 5 cm Tilapia
rnossambica. These fish grew very rapidly and reached a maximum
size of 36 cm in eight months. They were fished by cast-net and by
draining and gave a crop of fish a t the impressive rate of 1 500 lblacrel
annum.
Pakrasi et al. (1964) state that Tilapia and carp do well in the
brackish-water impounded paddy fields in the delta area of West
Bengal where they play a part in the high rate of fish production ( 3 600
kglhectarelannum).
Schuster found that Tilapia could be grown together with Chanos.
In two ponds of total area 240 acres, there was a fish crop of 99 lb of
Chanos, 227 lb of Tilapia, 31 lb of other fish, and 114 lb of prawns.
179
ance of the salt marsh, from which they were made, by the end of the
war.
Though conditions had prevented any of the usual measures of
pond maintenance, the Tilapia found suitable conditions, so that they
gave rise t o a productive fishery, chiefly with cast nets a t monthly
intervals. Nevertheless, the pond soil showed no sign of exhaustion,
the production of blue-greens and diatoms was abundant. The
green algae which also flourished were kept in check by the Tilapia,
which thus also helped to solve a health problem, for malarial mosquitoes bred dangerously among the floating masses of green algae.
Schuster found that, in brackish water, Tilapia could grow t o a
weight of a pound or more in eight months-a far better performance
than in fresh water ; but commercially the best results were obtained
by marketing at about 3-5 ounces weight, which would be at lengths
of about 17-22 cm.
It proved possible, in fertile shore ponds, t o cultivate prawns and
Tilapia together, the Tilapia breeding naturally, and the prawns
entering the ponds as larvae with the filling water. Schuster quotes
statistics of the fishpond system, " Heemrad ", near Djakarta where,
in 1947-8, prawns were produced a t the rate of 60-85 lb per acre per
annum, as well as 170-260 lb of Tilapia.
Tilapia has established itself in the Singapore prawn ponds, and
some reasonably well-grown specimens (up to 270g in weight) can
be found when required. Le Mare (1950) showed convincingly the value
of T . mossambica as a fish for brackish-water fish culture. He empoldered an area of saline swamp in Singapore, on which were eight
Malay houses, built, as is customary, on stilts over the water, and
therefore whose household wastes fertilized the area. No other fertilizer
was used, and the salinity was maintained at 20%,. The shrimp
Acetes, penaeid prawns, and fish, especially grey mullet, entered the
pond with the water, and the filled pond was stocked with 5 cm Tilapia
rnossambica. These fish grew very rapidly and reached a maximum
size of 36 cm in eight months. They were fished by cast-net and by
draining and gave a crop of fish a t the impressive rate of 1 500 lblacrel
annum.
Pakrasi et al. (1964) state that Tilapia and carp do well in the
brackish-water impounded paddy fields in the delta area of West
Bengal where they play a part in the high rate of fish production ( 3 600
kglhectarelannum).
Schuster found that Tilapia could be grown together with Chanos.
In two ponds of total area 240 acres, there was a fish crop of 99 lb of
Chanos, 227 lb of Tilapia, 31 lb of other fish, and 114 lb of prawns.