Grow out carp farming

Stocking density
The ponds for rearing of grow out also require all pond preparation practices like nursery
and fingerlings. The ponds are usually stocked with 30 – 40 percent of surface feeders, 30 – 35
percent of column feeders and 30 – 40 percent of bottom feeders. The fingerlings of 60 – 100 mm
size are considered ideal for rearing in pond. When small size fishes are stocked higher mortality
and poor growth performance occur in initial months. 50 – 100 g fingerlings are suitable for rearing
in cement cisterns to realize a survival rate of about 95 percent.

Many studies have been conducted over the years to enhance fish production and raise the
income. The recent trend in carp culture technology is that it has transformed from single stock
multiple harvest to multiple stock multiple harvests. The single time stocking and single harvest
with the stocking of 8000 fingerlings is termed single stocking and single harvest. Single stocking
and multi harvest is, when the stocking density is more than single stocking by about one and half
times. It is done with the intention to harvest 50 percent after 6 months. In multiple stocking and
multiple harvest, the stocking density is the same as single stocking (8000/ha). The harvest can be
done when fish reach 500g. After every harvest, the stocking is done to replenish the harvested
number. The stocking number should be maintained. In single stocking, with the ideal stocking
density of 8000 fingerlings, a production of around 5 tons/ha/yr is realised in composite fish
culture. In temporary ponds, with a stocking density of 10,000 – 12,000 fingerlings, the fish would
grow about 300 – 400 g in 5 – 6 months. If bigger size is required stocking size should be more than
100 g with a density of 3000 – 4000. It can then produce around 1 kg fish in 10 – 12 months.

Cultural practices

The cultural practices have evolved in the county to suit species selection, water availability,
fertilizer dosage, feed usage, etc. The carp culture technology can be categorized into the low input,
Medium and high input systems.
Low input system culture method is one in which limited amount of inputs are used. In fertilizer
based low input culture system, a fish production of 500 – 600 kg/ha/yr has been realised without
addition of feed. The pond is well prepared, mahua oilcake (@ 2500 kg/ha) or urea and bleaching
powder (5mg/l of each) is added. A production of 2000kg is possible with stocking density of
3000/ha with fingerlings of minimum of 50 mm.
Under medium input system, the production can be 4 – 8 tons/ha/yr when feed is provided along
with fertilizer.
High input carp culture, also known as intensive or semi-intensive culture system, is one in
which fertilizer, feed along with occasional water exchange are being taken up. Higher quantity of
fish feed and water are used in this system with not much variation in fertilizer quantity. The fish
production can be a maximum of 8 tons/ha/yr from the stocking density of 4000/ha of exotic carp
and 20 percent water exchange.
Food is the main governing factor in fish growth. Naturally available food is inadequate and
thereby supplementary feed is necessary for enhanced fish production. Feeding preferably twice a
day is advocated. Excess and under feeding should be avoided as both affect fish growth.

Health management
The fishes are sampled periodically to check the health of fish, including growth, presence
of parasite and bacterial diseases. Carps in grow-out pond are likely to be infected by Epizootic
Ulcerative Syndrome and Argulus infection especially in the winter season. This can be diagnosed
using CIFAX at 1 liter/ha in water.

Water quality management
The physico-chemical parameters of pond water should be within optimum limits for
better fish growth and survival. Water quality is not an issue for low stocking density and low yield
harvest but is one of the major concern when the stocking density is higher. The dissolved oxygen is
an important factor to be monitored. Dissolved oxygen, the source of which is from the atmosphere
and also through photosynthesis by plankton and macrophytes, should be ideally about 5 mg/l.
This can be maintained by using aerator (paddle wheel, aspirators and submersible pond aerator).
The paddle wheel aerator is appropriate for ponds of depth 1 to 1.5m. The other two aerators have
higher injection capacity of air into the water and hence can be used appropriately. A simple way of
aeration is to circulate the pond water. It can be done using a pump which can take water from the
lower surface of the pond and splash it into the same pond.

Harvest
Fishes are harvested after 10 – 12 months in single stock and single harvest system and
regular in multiple stock and multiple harvests. In one year culture, the catla grows about 1kg and
Rohu and Mrigal grow about 600 – 700 g. When the fingerling stocking size is of 150 – 200g, a
harvest of fishes weighing more than one kg is possible.

Grow out carp farming

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