High-yield culture management techniques of intensive culture of grass carp in ponds

Grass carp grows rapidly, the fastest growth period of body length is 1-2 years old, and the body weight growth of 2-3 years old is the fastest. When the 4-year-old fish reached sexual maturity, the growth slowed down significantly. In the natural state, the body length of 1 winter age fish is about 340 mm, the weight is about 750 g, the body length of 2 winter age fish is about 600 mm, the weight is 3.5 kg, the body length of 3 winter age fish is about 680 mm, the weight is about 5 kg, the body length of 4 winter age fish is about 740 mm, the weight is about 7 kg, the weight of 5 winter age fish is about 780 mm, the weight is about 7.5 kg, and the largest individual is about 35 kg.

Culture condition

1. Pond conditions: the area is 5-10 mu, the bottom is flat, the bottom is loam, the sediment is 10-20 cm, and the water depth is about 2 meters. The pond chooses the east-west direction, and each pond is equipped with a 3-kilowatt turbine aerator and a 4-inch water pump.

2. Clear field disinfection: in the case of dry ponds (5-10 cm of stagnant water), 100 kg of quicklime is used to sprinkle 100 kg of chemical pulp in the whole pool or 10 kg of bleach per mu, and after the solution of warm water, the whole pool is sprinkled, so that no dead corners are left and disease-causing bacteria are thoroughly killed.

3. Water quality: ph 7.5-8.5, the transparency of pond water in the peak culture season (June-September) is about 30 cm, and the organic oxygen consumption (COD) is 18-20 mg / L.

4. Fish species selection: grass carp should choose individuals with golden color, harmless appearance, lively and strong weight of about 100 grams per tail. At the same time, because the two major diseases of grass carp bleeding and enteritis are easy to infect the same year's fish species, it is better to choose 2-year-old seedlings.

5. Fish restocking

A, stocking time: spring stocking or autumn stocking, spring stocking time is when the water temperature rises to more than 12 ℃, and autumn stocking time is when the water temperature is between 15 and 12 ℃.

B, stocking mode: the stocking mode can be divided into two types: primary culture and mixed culture, mainly the main culture mode. The main culture mode of grass carp accounts for 80%-85%, with 20%-15% silver carp, bighead carp, bream and crucian carp.

C, stocking specification and density: when the stocking specification of grass carp is 15~20cm, the suitable stocking density is 14001600 / mu. When the stocking specification of grass carp is 20~25cm, the suitable stocking density is 1200 ~ 1400 fish / mu.

5. Fish fingerling disinfection: fish fry are soaked in 3%-4% salt water or potassium permanganate 20mg/L or povidone copper iodine (containing 1% available iodine) 20~30mg/L for 5 minutes for 10 minutes before stocking.

6. Fish feed: the feed used for intensive cultivation of grass carp in ponds is mainly compound feed accounting for 85%, supplemented by green feed for 15%.

7. Feeding management: feeding in intensive ponds is the main work in the stage of feeding and management, including conventional feed feeding and drug bait feeding. The feeding method adopts artificial domestication and fixed-point feeding, and strictly adheres to fixed-quality, quantitative, timing and fixed-point feeding. The specific practices are as follows:

A, conventional feed feeding: mainly to feed pellet feed, feed protein content of 28% 32%, auxiliary green feed. Feed feeding follows the principle of "coarsening before finishing". The feeding times were 2-4 times a day from mid-March to May, 3 times a day from June to mid-August, and 4 times a day from mid-August to October. Starting from June, feed green fodder once a day, the amount of feeding should not be too large, 80% full is appropriate, strictly prevent oversatiety and hunger. Generally, the daily feeding amount is controlled at about 3% or 5% of the body weight of eating fish, and it is fed twice in the morning and in the afternoon. The amount of feeding accounts for about 20% of the daily feeding in the morning and about 80% in the afternoon.

From March to June, the pellet feed with a protein content of 28% was mainly fed, with a daily feeding rate of 3%, and an appropriate amount of green feed.

From July to September, the daily feeding rate of pellet feed is about 1.5%, and the protein content of pellet feed is 28%. Increase the amount of green feed to control the occurrence of fish disease.

Pellet feed with a protein content of 32% was fed from October to November.

After feeding pellet feed continuously for a period of time, the pellet feed should be stopped for one week, and the raw grain feed should be fed at intervals. Usually pay attention to adding appropriate amount of vitamins and other drugs in the feed to avoid a large number of deaths caused by diseases such as hepatobiliary syndrome of grass carp.

B. points for attention in feeding: "three looks" should be achieved in feeding.

Depending on the season: the water temperature is different in the four seasons, so that you can start eating early and stop eating at night, and make the fish eat well in the middle, so as to promote the growth of fish.

Look at the weather: the weather is sunny, the dissolved oxygen in the water is high, the fish intake is exuberant, it is appropriate to throw more; the weather is muggy, the dissolved oxygen in the water is low, the fish should lose appetite or not, and you can stop eating in case of strong wind and heavy rain.

Look at water color: water color is a comprehensive phenomenon of water quality, water quality is refreshing, water color is normal, fish intake is exuberant, normal feeding, water color is too strong, fish floating head should be less or stop feeding.

C. Feed feeding points

Storage time should not be too long: pellet feed contains 1214% moisture in the production process, storage time is long, easy to deliquescence, mildew, affecting the use value of pellet feed, after feeding, the fish is easy to get sick. Therefore, the storage time should not be too long.

Increase the feeding times: the fish has no stomach and the feed stays in the intestinal tract for a short time, so under the condition that the total feeding amount is constant, the feeding times should be increased and each feeding amount should be reduced, so that the fish will always be in a state of semi-starvation, which can improve the feed utilization rate and reduce the feed coefficient.

It is necessary to have a certain feeding area and time: in multi-species mixed culture ponds, crucian carp and grass carp grab food quickly and eat a large amount of food, while carp eat "gentle", the corresponding food intake is less, which often affects its growth. Therefore, it is necessary to domesticate the fish for a short time before using pellet feed, so that the fish can form a fixed feeding ground and a fixed time feeding habit, each time should be distributed evenly, the feeding time is not less than 30 minutes, and the feeding area is 40 to 60 square meters, so that each fish can get bait.

The particle size should be reasonable: when the fish are stocked, the water temperature is low, the growth is slow, the size of the pellet feed is small, and the particle size of the pellet feed is controlled at 2 mm. With the rise of air temperature and the growth of fish species, the feed particle size is 3 to 3.5 mm in the middle of culture and 4 to 4.5 mm in the later stage of culture.

Add salt and allicin to prevent fish disease: when making pellet feed, mix the right amount of salt and allicin evenly into the raw material, which can disinfect and sterilize and prevent fish disease.

B, bait feeding: sulfonamide guanidine is used and made into floating feed. The practice is as follows:

Every 5 grams of sulfadiazine mix 1 jin of wheat bran, add 3 taels of elm bark powder or sweet potato powder, mix with hot water, press into small pieces, dry and set aside.

Feeding method: the bait was mixed into the granules. On the first day, 1 gram was used according to the body weight of pond fish, and the daily dose was reduced by half from the second to the sixth day. Once a day, 6 days as a cycle, feeding every month to one and a half months.