The artificial propagation of golden carp mainly includes several successive stages of broodstock breeding, artificial insemination, hatching and larval management. ?
1 Broodstock breeding
Breeding broodstock that is strong and fertile can produce ideal eggs, fertilization, hatching effects, and excellent fish eggs and juveniles. For the broodstock that is to be used as the next year to lay eggs, the annual culturing is started from the spring. The selection criteria for broodstock are robust, disease-free, and ages 4-5 years.
1.1 Environmental conditions for broodstock breeding
The area of ​​the fish pond required for broodstock cultivation is usually 100-300 square meters. The specific situation should be determined according to the direction and scale of development. The water depth is generally between 1 and 1.4 meters and the water injection volume is 50 litres/second. The suitable incubation temperature is 12-13°C and the lower limit is 4-5°C. The water temperature 6 months before spawning should not exceed 12°C. Cultivating at this temperature is good for obtaining good eggs. The suitable density for broodstock breeding is 5-10 kg/m2.
1.2 Management of broodstock breeding
The artificial reproductive efficiency of golden mullet is closely related to the broodstock's cultivation and management. In order to cultivate broodstock, special management should be conducted. In particular, attention should be paid to the regulation and management of environmental conditions and feed nutrition. The most important external factors affecting gonad development in broodstock are:
(1) Water temperature
When the appropriate water temperature for the development of gonadal gonads is below 13°C and above 15°C, not only abnormal eggs but also the rate of eye drops will be significantly reduced. When the water temperature is below 4°C, the gonadal development stops and the spawning period is postponed.
(2) Lighting
From the different lighting requirements can be divided into two categories, one is long-day fish, one is a short-day fish. The golden pheasant is a short-day fish. Sunshine time is within 12 hours. The goldfish have a rapid gonadal development. If the light develops for more than 12 hours, it will slow down. Therefore, to make the gonads grow well, the sunshine hours should be controlled within 12 hours as much as possible.
(3) Sexual stimulation
In nature, male fish have a stimulatory effect on the gonad development of females. Therefore, male and female polyculture is adopted during the broodstock breeding process of the golden mullet, and the stock is maintained one month before spawning. The proportion of males and females reared by broodstock can be controlled around 4:1.
(4) Feed for broodstock cultivation
The quality of golden carp fish eggs is related to the quality of broodstock food. The crude protein used for broodstock's full-priced feed is no less than 38%, crude fat is no more than 6%, and carbohydrates are no more than 12%. Vitamin A is not less than 20,000 international units per kilogram of feed, vitamin D is not less than 2,000 international units, and vitamin E is not less than 75 milligrams. The addition of yeast powder and crawfish powder, shrimp and crab powder contributes to the improvement of the egg mass. Crayfish powder and the like cannot play a role in coloring the egg red pigment.
To cultivate gonads with well-developed gonads, a certain amount of nutrient-rich concentrate must be fed. In order to improve the quality of fish eggs, feed formulation should be adjusted accordingly with the different stages of gonadal development to meet the nutritional needs of broodstock at different stages of development.
2 Male and female identification
The identification of males and females is mainly based on body color, head, and snout. Deep body color, head and mouth large, mandibular upward bending, covering the upper jaw, slightly raised back, abdominal hard, inelastic, vent hole is not prominent, the tip of the kiss for the male fish. Body color is lighter than that of the male, with a small head and mouth, no back uplift, a large abdomen, softness, and elasticity. The genital hole is prominent and the blunt and rounded ends are female fish.
3 Hatching
3.1 Ecological requirements for hatching
Sunlight and mechanical vibrations have a lethal effect on fertilized eggs, and reflected light also has an adverse effect on the development of eggs. Incubation water requires the clarification of water quality without impurities. The optimal water temperature for hatching was 9°C, and the suitable temperature range was 7-13°C. Below this range, the number of hatching days was prolonged and the hatching effect was not good. Above this range, the hatching eye rate decreased and the malformed larvae increased. The dissolved oxygen in the incubation water should be higher than 6.5 mg/l.
3.2 Management of fertilized egg hatching
The goldfish, after fertilization, was swollen and placed in an incubator for hatching. Incubators currently use a combination of barrel incubators and flat columns. Incubation water overflows from the upper part of the fish eggs in the lower flow path, and the water injection volume per barrel is 4-7 liters/min. The malachite green solution was disinfected every 4 days for 1 hour to inhibit the growth of water mold. Incubation to a cumulative temperature of 220 degrees days, when the eye point is obvious, go into the flat groove to continue.
Artificially picked dead eggs during hatching. There are small troughs flowing from the bottom to the top in the troughs. Each trough can contain 4–60,000 ovums, laying the eggs in a horizontal row. The tank and tank combination method can greatly save water and floor space. The hatchery can be placed in a rack and can hatch nearly 1 million fish eggs in an area of ​​8 barrels per square meter. Two rows of troughs are arranged for easy inspection and management, and they can be kept in the original trough for 2-3 weeks after emergence. Each hatching cycle keeps the eggs in a quiet state and uses strict light protection measures.
3.3 Management of Ophthalmology
The optimum temperature for hatching eggs is 9°C, so the temperature should be controlled at 7-13°C. Ophthalmic eggs consume more oxygen, and even if the water is stopped for a short period of time, it will be too dense to cause anaerobic suffocation. Therefore, the supply of running water must be guaranteed during incubation. In addition, it should be kept quiet during the entire incubation process to prevent any noise interference and vibrations during handling. Although the resistance of the ovum to the vibration is relatively enhanced, excessive vibrations should still be prevented.
4 Management of hatched larvae
Different names for different stages of development of golden mullet. Hatching up to floating, known as larvae; floating up to feeding, called floating juvenile fish; feeding to about 5 months of age, known as juvenile fish; 5 months of age to anniversary, called the year of the fish; 1-2 anniversary, said One-year-old fish.
The barrel-type incubator hatches the fertilized eggs to 220 days and then promptly transfers them into a horizontal tank for incubation. The volume of eggs is laid on the floor of the tank. The water injection per 10,000 eggs is 8-10 liters per minute. Remove dead eggs in time. When the fish eggs in the tank begin to have broken film larvae, inspections should be intensified to clear the egg skins and dead seedlings in time. Attention should be paid to the cleanliness of the breeding environment. Slots are often brushed to keep the water flowing.
The newly hatched larvae have a weak physique, a thin body color, a yolk sac, lying on the bottom of the trough, and a body length of 15 mm. The yolk sac absorbs nutrients and continues to develop. After 16-20 days, the yolk sac gradually absorbs. Increased melanin and increased swimming ability. If the tank is not enough for use at this time, it can be moved to the juvenile fish pond without direct light to continue absorbing the yolk sac, so that the vacant flat grooves continue to be placed in the oming eggs of the forthcoming membrane, and the cycle can be used again and again.
5 Fry culture
The first month of floating-fish fry feeding is the most difficult and most technical stage in goldfish culture. The first step in this stage is to watch for survival, followed by growth. The newly hatched fry is very tender and weak, because the yolk sac supplies nutrients, and no feeding is required at this time. When the yolk sac absorbs more than 2/3 of the total, most of the fry begin to feed on the fly, and at this time it is timely to feed the nutritious and easily digestible food. At the beginning, you can feed yolks, leeches, and silkworms. It needs to be fed 6-8 times a day. After 20 days of feeding, the general body is as long as 2.5 cm and the body weight is 0.2 g. It can be fed to the breeding pond.
6 Fish Breeding
The stocking density of fry and fingerling varies with fish size, water temperature and water injection. Fry is usually kept under conditions where the water temperature is slightly lower and it is not easy to get sick. The survival rate is high.
With the growth of seedlings, the content of animal protein such as fish meal in feeds can be gradually reduced, and the proportion of plant proteins can be increased.
The gold carp feed is processed into pellets or crumbs. The feeding amount is adjusted at any time according to the specifications of the fish body and the weather. During the rearing process, the growth is inconsistent due to differences in the physique and feeding capacity of the seed, and the fish has a large amount. Small, so when the fry grows to 2 grams, it needs to be screened and separated. The selected fry will be reared according to the size and size of the fish, so as to prevent the big fish from competing for food and affecting the growth of the small fish. The screening work can be performed once every 20 days to 40 days, and the stocking density can be adjusted according to the size of individual seedlings.
7 Adult rearing
In order to obtain high conservation efficiency, it is necessary to strive for the maximum production volume in terms of limited fish pond area and water consumption. For this reason, maximum stocking density and good feed efficiency should always be maintained in all fish ponds.
Feed is the key to high-density cultivation. The quality of the feed is critical because the nutrients of the fish under compact conditions are completely dependent on the artificial feed intake. The full-price feed used for gold carp fingerlings and adult fish has 40% to 45% crude protein, 6% to 16% crude fat, 2% to 5% crude fiber, and 5% to 13% ash. %, moisture 8%-12%. The daily feeding amount is generally not more than 3% of the total weight of the fish, and the feeding is performed 2-3 times daily.
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