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Somsuk Singholka*

The giant freshwater prawn, Macrobrachium rosenbergii De Man, is native to Thailand and other Asean countries that bodies of fresh water are connected to the sea. These include Australia, India, Sri Lanka, Bangladesh, Pakistan, Indonesia, Philipines Malaysia, Vietnam and Cambodia in Thailand, it found abundant in Center Plain, East, and in the Southern of Country.

The giant freshwater prawn is and delicious protein food. This production did not meet the local demand. The prawn are now costly: the market price in 100 – 150 baht per kilogram against that of 20 baht per kilogram in 1957. In order to gain the production of this species, the government has released funds to construct a Central Giant Freshwater prawn Research and Training Station at Bangpakong District Chachoengsao Province.

Central Giant Freshwater Prawn Research and Training Station is located at Bangpakong District, Chachoengsao Province, named Chachoengsao Macrobrachium Research Center, in 31 acres area, it consist of resident area, office, Lab and 168 ponds. Construction of this station was started in November, 1974 and completion is expected to be in 1978. This station will be the main site of the project.

The purpose of this project is to establish central research and training station and expand and improve the hatchery work so that adequate supplies of post larvae and juveniles are produced for the farmer and restock in the natural water. A pond demonstration unit will be estrablished for the conduct of extensive investigations, development of improved rearing technique and extensive service to assist the farmer.

* Chief, Machobrachium Research Center


At Chachoengsao Macrobrachium Research Center, 10 – 15 female prawn bearing eggs are put into each 15 tons concrete hatching tank, which has the width, length and depth, in centimeters, 150, 1500 and 100 respectively. Each tank is pave by Poly - ethyline resin. It is half filled with brackish water (salinity 9 ppt.), prepared by diluting seawater with locally available under - ground water. The hatching tanks are aerated by air blower.

When the eggs are found to have hatching, the females are immediately removed and the brackish water rich in plankton (salinity 12 ppt.) is slowly added to the depth of 90 cm. The tanks are partially covered with plastic during the day to provide shade from direct sun light, and completely covered at night to minimize cooling of the water.

Brackish water enrich in plankton for hatchery is prepared in 50m2 tanks. Seawater is diluted to the salinity of 12 ppm. and 30 – 50 kg. of Tilapia sp. daily and the tanks are also aerated. Five to six days later the water will be rich in plankton. The color is deep green. That is ready to supply to the hatching tanks.

Three days after hatching, Artemia nauplii is fed to the larvae started with 10 gm/tank, 2 time a days, five days after hatching, the feeding is changed finely minced fish flosh is given during the daytime, five to six time a day, and Artemia during the nighttime. The tank is cleaned, flushed and including uneaten food is siphoned out every day.

The majority of the larval will complete the metamorphosis and become the juveniles in 25 days following the hatching. The salinity of the hatching tank is then slowly reduced and finally the juveniles live in fresh water.

The juveniles are then transfered to the nursery tank (50 cu.m.). The stocking rate is 2,000/m2. Plastic net is put in the tank to reduce density or sunlight and be the shelter of the juveniles. They are nursed for two weeks and then release to the farmers.

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