Farming freshwater prawns A manual for the culture of ... - eXtension

Electricity is desirable, although it need not be the sole source of energy, for powering
lights, wells and feed-making equipment. The most suitable power source to use is
entirely site-specific and depends upon such factors as equipment availability, unit power
costs and the characteristics of the site and its water supply. Generating electricity on the
farm may be cheaper than running a new supply from the nearest point on the national
power grid. Where a power failure would quickly result in severe losses, for example in
farms operating highly intensive systems dependent on aeration, a back-up power source
(usually a diesel generator) is essential.
The ideal would be for you to be able to move water within your site by gravity but
this depends on the nature of the site. In practice, most farms use electric or fuel-driven
pumps for supplying water to the ponds (Figure 9) and some also use them for draining the
ponds during harvesting (Figure 10). Some small farms prepare cooked feed using wood as
a fuel source, while others utilize the time-old methods of wind and water power for transporting
water. Windmills and water-wheels can also be used to pump water for filling
ponds, or to generate a farm supply of electricity.
Figure 9
Pumps can be
powered by old
diesel bus engines
(Thailand)
Figure 10
More expensive
pumps are used
in some countries;
this one is being used
to harvest freshwater
prawns (Hawaii)
SOURCE: HASSANAI KONGKEO
SOURCE: SPENCER MALECHA
CHOOSING YOUR SITE: FRY AND CONSUMABLES
There is no fundamental technical difficulty in transporting postlarval freshwater prawns
long distances by road, rail or even air. However, you need provide vehicle access close to
the pond site. It is not satisfactory to bring PL long distances to your grow-out site if there
are going to be further delays due to poor local access. In selecting the site of your farm, it
is important to assess the cost of obtaining PL. Transport costs can add enormously to basic
stocking costs. Also, PL prices themselves tend to rise as the distance between the farm and
the nearest hatchery increases (because there is less competition between hatchery operators).
Also, you need to consider the availability and cost of getting feeds to your potential
farm site. A large farm (say 40 ha) which achieves an average output of 2 500 kg/ha/yr, for
example, would require an average of about 5 mt of dry feed per week. Supposing that this
feed is delivered to the site monthly, it would arrive in 20 mt batches; this means you need
good vehicle access to the site. You would also need to provide clean, dry, cool, and secure
feed storage facilities on the site. Similar factors apply to the supply of other consumables,
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