A Detailed Guide to Black Carp Farming Techniques: Practical Methods Explained in One Article

1. Feeding habits  The black carp is a carnivorous fish; at the fry and fingerling stages it mainly feeds on zooplankton. When the body length reaches about 15cm, it changes its feeding habits and begins to feed on small snails and the like. As the pharyngeal teeth develop, their crushing function strengthens, and juvenile fish feed mainly on mollusks, such as mussels, river snails and the like. In addition, it also eats shrimp, crabs and insect larvae.

2. Growth  The black carp is large in size and grows rapidly, with a maximum weight of up to 70kg. A 1-year-old fish can grow to 500g, a 2-year-old fish to 2.53 kg, and a 3-year-old fish in a good environment can reach 6.57.5 kg. The body length of the black carp grows fastest at 12 years of age, and after 5 years of age its body length growth rate slows; weight gain is fastest at 34 years of age, and it continues to gain weight thereafter.

3. Reproduction  The black carp is a migratory fish; it grows and develops in the affiliated water bodies of rivers, enters the rivers in winter to overwinter, and after the beginning of spring the overwintering parent fish swim upstream, and during the upstream migration their gonads develop rapidly to maturity, spawning in the spawning grounds of the main stream of the river, and after spawning the parent fish again enter the affiliated water bodies to fatten up. Each year, May and June are the breeding season, requiring a water temperature of 1828°C. When the spawning ground rises in water, the flow velocity is 12m/s, and the flow pattern becomes turbulent, the parent fish begin to spawn. Black carp eggs are pelagic, and hatch and develop with the water flow. The age of sexual maturity of the black carp is: female fish 57 years, male fish 45 years. Spawning type: sexually mature individuals mature their gonads once a year and spawn once. The fecundity of the black carp increases markedly with body weight; generally, a parent fish of 1520kg has a fecundity of about 600,0001,000,000 eggs.

II. Artificial breeding

1. Sources of parent fish

Natural fry and fingerlings from river basins, or fry and fingerlings produced by a national original seed farm, or adult black carp selectively collected from natural germplasm resource banks, or from natural waters such as rivers, reservoirs and lakes that have not been artificially stocked, and then cultivated to serve as parent fish. Offspring of inbreeding must not be used as a source of parent fish……

2. Parent fish cultivation

(1) Parent fish are required to be over 6 years old and weigh more than 15 kilograms, stocked at a female-to-male ratio of 1:1.5, with about 10 black carp of 15~20 kilograms per mu.

(2) The parent fish pond should have a flat bottom, preferably sandy loam soil, and maintain fresh water quality; feed mainly on river snails, clams and mussel meat, supplemented with a small amount of soybean cake and malt, and regularly add and flush new water. Generally, in winter, flush water once a month and maintain a water depth of more than 2 meters. After the beginning of spring, lower the water level to help raise the pond water temperature, flush water once a week, and from mid-April begin to increase the frequency of flushing, flushing once every 2~3 days, to promote gonad maturation.

(3) In the parent fish pond, stock a small amount of silver carp and bighead carp to regulate water quality, and at the same time appropriately polyculture carnivorous fish such as snakehead and California bass, etc., to prey on wild trash fish in the pond, which is beneficial to parent fish cultivation and also increases pond returns.

3. Induced spawning of parent fish

(1) Time and water temperature for induced spawning: in the middle and lower reaches of the Yangtze River, the time for induced spawning is mid-to-late May, and the most suitable water temperature for induced spawning is 25~28°C.

(2) Selection of parent fish: the maturity of the parent fish directly affects the effect of induced spawning. The criteria for identification are that when the abdomen of the male fish is gently squeezed, semen flows out and disperses immediately upon contact with water; the abdomen of the female fish is enlarged, soft and elastic, and the scales on the abdomen are relatively sparse. To improve the maturity of the population, a net can be cast for inspection in mid-April, and for those with poorer maturity, according to individual size and maturity, inject LRH-A3~5 micrograms per fish respectively.

(3) Injection of spawning agents: commonly used spawning agents are LRH-A, DOM, PG, etc.; usually a mixture of two gives a better effect. Our farm uses three injections, with a high induced spawning rate, as high as over 95%. The first injection is LRH-A1 microgram per kilogram for each parent fish, with an interval of 20 hours; the second injection is LRH-A5 micrograms per kilogram for each parent fish, with an interval of 8 hours; the third injection is LTH-A20 micrograms per kilogram plus PG3~4 milligrams or plus DOM4~5 milligrams for female parent fish, and the dose for male parent fish is 1/3~1/2 of the dose for female parent fish depending on the specific situation; all injections use thoracic cavity injection.

4. Estrus and artificial insemination

The length of the effect time varies with the water temperature. According to observation, when the water temperature is 26~28 degrees, the effect time is 6~7 hours. When the parent fish reach the expected time of estrus and in combination with the actual estrus condition, catch the parent fish for artificial insemination. During insemination, be careful to act gently and quickly; when mixing sperm and eggs, appropriately add 0.6% physiological saline to prolong the insemination time, and during insemination avoid direct sunlight and rain splashing in, to improve the fertilization rate. The normal fertilization rate reaches over 90%.

5. Hatching

Put the water-absorbed fertilized eggs into a hatching circular channel or hatching jar for hatching; the water flow rate should be such that it can wash the fertilized eggs up to tumble. The water used for hatching should be supplied and discharged separately and should not be recycled. After the fry emerge from the membrane, the water flow should be appropriately increased to prevent the fry from sinking and suffocating to death. 24 hours after the fish fry hatch, the water flow should be appropriately reduced to avoid excessive water flow consuming the fry's energy. At the same developmental stage, the water flow rate should be lower during the day than at night; if the weather is abnormal and the temperature difference is large, it should be appropriately reduced to avoid excessive water flow consuming the fry's energy. At the same developmental stage, the water flow rate should be lower during the day than at night; if the weather is abnormal and the temperature difference is large, the water flow should be appropriately increased.