Abstract:
Government hatcheries maintain the brood stocks of Genetically Improved
Farmed Tilapia (GIFT) to supply fry and fingerlings for stocking
programmes. The demand for fry cannot be fulfilled by the production of
these hatcheries. To address this problem an experimental mini hatchery was
established. A bricked hut (3m x 3m) with asbestos roofing, owned by a
fisherman at Kattakaduwa, Hambantota was used as the hatchery. Water re circulating system having an overhead tank (1000 L), ground level storing
tank (1500 L), and two large gravel filters (25L) in order to filter the water
entering and leaving the hatchery was established. Transparent plastic bottles
(4L, 22cm in height) and plastic trays (40cm x 28cm x 4cm) were used as
incubation jars. Inflow water was supplied to the bottom of the each bottle
and 28cm side of the trays through 1.25 cm PVC pipe. Outflow water was
removed from the top of the bottle via a 2.5 cm pipe and through a series of
holes pierced at the 40cm sides of the trays. Stocking density for eggs and
yolk sac fry were 250/L. Different flow rates for incubation of eggs and for
survival of yolk-sac fry were trialled. Plastic bottles were the best container
for incubation of eggs resulting over 80% hatchability. Plastic trays proved
the most suitable container (90% survival) for development of yolk sac
larvae. Optimized flow rates were 2.7 L min-1 for egg incubation and 5.4 L
min-1 for yolk-sac fry. Total cost for the hatchery was approximately Rs.
77000. As one hatchery cycle lasts for approximately 10 days, this cost is
recoverable in few rounds of hatchery cycles. No high technology being
involved in construction, this mini hatchery provides a suitable system for
fry production for farmers to fulfil their own seed requirements.
