studies on improved practices of prawn farming for higher ...

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was followed below by rearing tank, for nauplii and zoea larvae, then
another one for mysis to PL1_5 stages and finally a large one for post
larvae.
The more favoured nursery approach necessitates rearing the
nauplii through different stages by supplying appropriate feed —- live
or inert. The success of any hatchery operation depends mainly on the
availability of the phyto plankton-— the meadows of the sea, because
the large scale production of molluscan, crustacean and fish larvae
mainly depend on mass culture of particular species of unicellular
algae as a food source in the early stages of development (Loosanoff
and Davis, 1963).
In the western hemisphere and in China multimillion dollar
hatcheries with high-tech facilities produce large number of seed stock
in controlled environment through out the year.
In south east Asia particularly in.Thailand, Taiwan, Indonesia
and Philippines, small hatcheries also known as backyard hatcheries
using low densities and imtreated water is of common occurrence. They
are often affected by bacterial and viral diseases and water quality.
Hatcheries have been marginally successful, as fast growing
giant tiger prawn E. monodon reaching a maximum of 336 mm does not
mature in captivity. Only the Chinese white shrimp E. chinensis is
well suited for captive maturation.
It takes about 6 weeks for the larvae from spawning to stocking
in grow out ponds to complete the hatchery cycle. However, hatcheries
remain as the weakest link in the production cycle.
In India, success was attained to spawn and rear most of the
cultivable species of shrimps in the laboratory using the Japanese
technology‘ with appropriate local alterations (Silas, 1978).