1. Breeding of common carp (Cyprinus carpio)

2. 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
Ranked third among the farmed finfishes in the world, next only to silver carp and grass carp
Introduced into India in 1939 from Germany (German strain)
It is an ideal species for aquaculture
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.
Figure: The common carp

3. Broodfish - reared in manured pond
Care of brood-stock: 
Broodfish - 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
Matures months in a tropical country; can spawn in the pond in the presence of weeds, twigs, etc.
Figure: A haul of common carp brooders Figure: Common carp attached to Hydrilla
being released in a pond for hatching

4. The fecundity is 0.5-1.0 lakh eggs per kg female
Hence, sex-wise segregation and rearing them in separate pond is necessary to avoid accidental spawning
The fecundity is lakh eggs per kg female
Females grow slightly faster than males
Figure: Water sprinklers provided in a spawnery Figure: Common carp spawn ready for
stocking in a nursery pond

5. Selection of brood fish and breeding technique
Artificial breeding is undertaken to enhance fry survival
Common carp is an asynchronous multiple spawners, releasing eggs in batches
Mature broodstock is identified based on their morphological characters
Male has round abdomen and whitish genital opening; oozes milt when pressured is applied on abdomen
Female is stouter, with soft and swollen abdomen; a few ova may ooze out when pressured 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

6. Aquatic plants like Hydrilla or Vallisnaria or Eichhornia, etc
Aquatic plants like Hydrilla or Vallisnaria or Eichhornia, etc. is released as a 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 as substratum for the attachment of eggs
Hydrilla
Vallisnaria
Eichhornia

7. 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.

8. 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

9. The stocking density of eggs is 50, ,00,000 eggs per hapa (2 x 1 x 1 m) or eggs per circular hatching tank
The eggs hatch in 36 – 72 hours 26 – 310C
The newly-hatched spawn is heavy (remain attached to hapa wall), 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

10. 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
They reach fry stage in days