Techniques of carp culture

Carp is a kind of economic fish of the order Cyprinidae, Cyprinidae and Cyprinus, which is distributed all over the country, and is one of the most important farmed fish species in China. Common varieties are scaly carp, mirror carp, red carp, Hebao carp and other local varieties, as well as Feng carp, Ying carp, Jian carp, all-female carp and other excellent varieties.

Biological characteristics

1. Morphological characteristics.

The fish is fusiform and slightly flat, the back is grayish black, the abdomen is light or grayish, and the body color is golden yellow below the lateral line and near the tail stalk (body color also varies according to breed, such as golden yellow, orange, pink, etc.). Mouth end position, horseshoe-shaped, 2 pairs of tentacles, jaws about 2 times as long as mustache. The scales are larger. The individual is larger, the common one is 0.5~2.5kg, the maximum can reach more than 15kg.

2. Diet and growth

Carp are omnivorous bottom fishes. Fish fry less than 3 cm in length mainly feed on rotifers and small cladocera, and feed on Cladocera, radial horn, rocky larva and other insect larvae more than 3 cm in length. They feed mainly on rockworms and ciliates when they are more than 20 cm long, and on benthos such as insect corbicula and fragments of aquatic plants above the first instar. Other food, such as algae, are also often found in the intestines. Due to miscellaneous eating habits, a wide range of food, low living conditions, fast growth, generally two-year-old can meet the commodity specifications, if raised with formula feed, one-year-old can reach the commodity specifications.

3. Life habits

Carp like to live in the lower layer of water, and the optimum water temperature for growth is 25-32 ℃. The growth of carp slows down significantly above 32 ℃ or below 15 ℃, and stops feeding below 10 ℃. The appropriate dissolved oxygen content is above 4.5mg/l, but if it is lower than 2mg/l, eat less, and 1mg/l will stop eating and float its head.

4. Reproductive characteristics

In general, the second age is sexually mature, and some individuals can also mature at the first age. The spawning season varies with the region, and it can lay eggs from March to August (April-June is the peak period), which belongs to the type of spawning in batches. The spawning ground is mostly in the shallow lake bay or river bay where there is a lot of water and grass, and the eggs are very sticky and firmly adhere to the water plants after spawning. the number of eggs varies with age and individual size, ranging from 15 to 800000 eggs. After egg production, seedlings can be hatched after 4-6 days at the water temperature of 15-20 ℃.

Breeding technology

1. Breeding of parent carp

(1) selection criteria

It has a good shape, strong vitality and no injury, and the ratio of body length to body height is 3:1, which has typical variety characteristics. The female fish at least 2 winter years old, the body weight 1.5kg, and the male fish more than 2 winter age 1kg are better. The carp in the first sexual maturity and aging stage have poor egg number and egg quality, so it is not suitable to be a parent fish.

(2) Sex identification

① non-reproductive season: the female fish is wide, the back is high, the head is small, the abdomen is large and soft, the thoracoventral fin is small and wide, the cloaca is flat or slightly prominent, with radiation fold; the male fish is long and narrow, the head is large, the abdomen is small and hard, the thoracoabdominal fin is large and sharp, and the anus is slightly concave inward, without parallel wrinkle.

② reproductive season: the abdomen of female fish is soft and round sac-shaped, the anus and reproductive foramen are larger, slightly reddish and prominent; the abdomen of male fish is smaller, the operculum, chest and ventral fin have obvious accessory sexual characteristics of "chasing stars", the anus and reproductive foramen are concave, not red and swollen, and milky semen flow out of the abdomen under light pressure.

(3) feeding and management

① breeding: parent fish breeding pond 1-2 mu, water depth about 1.2m, shelter from the wind to the sun, convenient injection and drainage, 150-200kg per mu, artificial reproduction, in order to prevent self-mating and spawning, male and female should be separated. Disinfect with quicklime or bleach before storage.

② management: strengthen the cultivation of parent carp and feed high-protein feed such as bean cake, silkworm pupa, fish meal and so on. In recent years, some manufacturers have developed parent fish feed, which is rich in ve and other vitamins, which can promote development and improve anti-stress ability with good results. At the same time, in the process of feeding, we should pay attention to adjust the water quality, often add fresh water, maintain micro-running water, in order to stimulate gonadal development.

2. Accelerate the birth and incubation

(1) timing of induced labor

When the water temperature rises and stabilizes above 16 ℃, it can induce labor. Usually during the period from Qingming Festival to Grain Rain, after the cold wave, when the temperature rises and stabilizes, labor can be induced.

(2) the mode of induced labor

① natural spawning is a very common way because of its small investment and scale.

◆ spawning pond: an area of 0.5-1mu, water depth of 1.2m, convenient for injection and drainage of the pond. Fish can be released one week after disinfection with quicklime.

◆ artificial fish nest: used to adhere to fish eggs. Choose materials with soft texture, good toughness, non-toxic and non-perishable materials, such as pine branches, brown pieces, polyethylene sheets (woven bags), poplar roots, etc., and wash, tie and disinfect them (0.3 ‰ formaldehyde or malachite green) before use. Straw is not suitable to be used as a fish nest because it is perishable.

◆ incubator: can also be used as a fish fry culture pond, the area should be small (1-2 mu), less silt, water depth of 1 meter sterilized pond. The inlet and outlet should be filtered with an encrypted mesh to prevent impurities from entering the pool and fish fry from escaping.

◆ and pool spawning: according to the male / female ratio of 1:1-1.535-30 to form a good mature parent carp pool, slowly add new water. At the same time, 1-8 iron wires are drawn on the surface of the water, and artificial fish nests are hung on the wires (or sandwiched in the middle and placed on the water surface with bamboo broken in two). Usually each group of parent fish should be equipped with 4-6 nests.

◆ management: usually spawn at 22:00-9:00 for 2-3 days, so fish nests should be inspected and cleaned every afternoon, the nests with eggs should be moved into the hatchery, and new nests should be replenished. If spawning after pooling is not good, the water level can be lowered to let the sun shine, and more ve can be added to the feed, or stimulated by micro-running water. In order to ensure the uniformity of fish fry, the eggs on the same day should be hatched together, which can also prevent the number of blind eggs from increasing due to the agglomeration of fish eggs.

Artificial spawning induced by ② is common in fish farms.

Injection of ◆: each kg female uses artificial chorionic gonadotropin (hcg) 600-1000iu or yellow-releasing hormone analogue (lrh-a) 30-50 micrograms, or reduces its dose in combination to halve the dose for males. Generally in a sunny day at 6 pm according to the predetermined dose at the base of the pectoral fin injection into the chest, and then moved into the spawning pool, and add fresh water for half an hour, water temperature 18 ℃ 6-15 hours after oestrus spawning (the higher the water temperature, the shorter the effect time, and vice versa).

◆ spawning and fertilization: after spawning, parent fish can lay eggs on their own in the pond, the method is the same as natural spawning. If artificial egg collection is carried out, it can be picked up before the most exciting part of the fish estrus, wipe off the moisture of the fish body with a towel, squeeze the eggs into a dry porcelain basin, quickly squeeze into the semen, stir with feathers, let them be fully fertilized, and then evenly smear the fertilized eggs on the fish nest and put them in the incubator to hatch. Or use talc solution to debonde and then hatch in running water. The seedlings can emerge in 3-5 days when the water temperature is 16-22 ℃.

(3) incubation management

① natural hatching: 30-500000 fertilized eggs per mu of pond should be put together on the same day to ensure the neat specifications of fish fry. Special attention should be paid to preventing water mildew. Fish nests with eggs can be washed in advance with 0.3 ‰ formaldehyde or malachite green.

② debonding and hatching: the key is to adjust the current velocity so that the fish eggs are suspended in the water without sinking. At the same time, it is necessary to prevent sand window clogging. Reduce the flow rate slightly when the fry are hatched to prevent the physical exertion of the current on the fry.

③ precautions: improving the hatching rate is the key to artificial reproduction. The main factors affecting the hatching rate are abrupt weather during the spawning period, poor water quality, low dissolved oxygen, parasitism of fish eggs by mold, etc., so we should try to prevent its harm.