Breeding of common carp
6.1. Distribution
and importance of common carp
- The common carp belongs to the family
Cyprinidae and Order Cypriniformes.
- C. carpio is a native to Central Asia and is
very widely distributed all over the world.
- It is widely cultured in temperate, tropical
and sub-tropical countries.
- It is ranked third among the farmed finfishes
in the world, next only to silver carp and grass carp.
- This exotic fish was first introduced into
India in 1939 from Germany (German strain).
- Later, the Asian strain was introduced from
Bangkok (Bangkok strain), in 1957.
- It is an ideal species for aquaculture and
fulfils all the requirements of an ideal species for aquaculture
- It breeds naturally in ponds, tanks,
reservoirs, etc. and spawns year-round, with two peaks, one during
February-March and the other during south-west monsoon.
- Grows to over one kg in one year.
6.2. Care of brood-stock
- Brood fish is reared in manured pond.
- Initially fed with conventional feed; as the
maturity advances they are fed with a special feed, consisting of rice
bran, oil cake, fish meal, cereals, grams, mineral and vitamin mixture.
- It matures within 4-6 months in a tropical
country like India and can spawn in the pond in the presence of weeds,
twigs, etc.
- Hence, sex-wise segregation and rearing them
in separate pond is necessary to avoid accidental spawning.
- The fecundity is 0.5-1.0 lakh eggs per kg
female.
- Females grow slightly faster than males.
6.3. Selection of broodfish and
breeding technique
- Artificial breeding is undertaken to enhance
fry survival.
- Common carp is an asynchronous multiple spawners,
releasing eggs in batches.
- Mature brood-stock is identified based on
their morphological characters.
- Male has round abdomen and whitish genital
opening; oozes milt when pressure is applied on abdomen.
- Female is stout, with soft and swollen abdomen;
a few ova may ooze out when pressure is applied on abdomen.
- Mature male and female are released at a ratio
of 2 : 1 in a cement cistern (25 m3) with running water.
- Aquatic plants like Hydrilla or Vallisnaria or
Eichhornia, etc. are used substratum in the cistern for the attachment of
eggs.
- The plants are disinfected with a solution of
KMnO4 and used at a ratio of 1:2 (female : substratum.
- In South-East Asian countries, kakabans (plant
fibres, normally coconut or palm, nailed between two pieces of bamboo) are
used as substratum for the attachment of eggs.
- The weight of female brooder is taken before
and after spawning in order to estimate quantity of eggs released,
allowing 5-10% towards loss of weight due to excreta.
- The total quantity of eggs released can be
calculated using the formula: Loss in weight (g) x 700, where, 700 is the
number of eggs per g ovary weight.
- After spawning, the brooders are removed from
the tank, disinfected and transferred to a prepared pond.
6.4.
Hatching of eggs
- The developing eggs which are attached to the
substratum are transferred to hatching hapa or circular tank for hatching
where running water is maintained.
- The eggs are adhesive, small (1-2 mm
diameter), with narrow perivitelline space, spherical and pale-yellow
(fertilized).
- Unfertilized eggs are opaque white.
- The stocking density of eggs is 50,000 -
1,00,000 eggs per hapa (2 x 1 x 1 m) or 25-30 lakh eggs per circular
hatching tank.
- The eggs hatch in 36 – 72 hours 26 – 31oC.
- The newly-hatched spawn is heavy (remain
attached to hapa wall), 4-5.6 mm long, with prominent eyes.
- The yolk-sac spawn remains in the hapa or tank
till it becomes free-swimming.
- Yolk-sac is completely absorbed in 3-4 days.
Rearing of spawn
- After the yolk-sac absorption, the spawn is
transferred to a prepared nursery pond for on-growing to fry/fingerling
stage.
- In the nursery pond the spawn is fed with a
mixture of rice bran and oil cake (1:1 ratio) till they reach fry stage in
15-20 days.
0 Comments