Culture techniques of freshwater crayfish

Freshwater lobster has the advantages of fast growth, large size, wide diet, strong adaptability, delicious meat and high economic value, so it has a broad market prospect. Breeding freshwater lobster is a good project with low investment, high benefit and simple operation.

Culture pond condition

The freshwater lobster does not have strict requirements on the conditions of the pond, so it is appropriate to choose the place with ventilation and sunny air, soil water conservation and no pollution to build the pond. The specification of the pond is generally 5 mu, the water depth is more than 1, 5 m, the bottom of sand and mud is flat, and the slope ratio of pond dam is 1 ∶ 3: 4, which has convenient conditions of inlet and drainage and anti-theft protection measures. As a hidden habitat for lobster, you can plant some aquatic plants or put a certain number of stones, bricks, tiles and other shelter in the pond, accounting for about 1 / 3 of the total water surface.

Preparation before stocking

The pond should have good intake and drainage facilities. Bamboo slices and gauze should be used around the pond to surround the 50-centimeter-high anti-escape wall. Set up shrimp habitats in aquaculture waters, such as rubble, bricks, stones, nets, old tires, grass dragons, etc. as shrimp nests for shrimp concealment and defense against enemies. Water hyacinth, water peanut, water floating lotus, Zizania caduciflora and other aquatic plants are planted around the pond, the coverage of which is generally 1 to 3 of the surface of the pond, to facilitate lobster shade and breed lobster's favorite plankton.

Generally, newly-built lobster ponds can be cleaned with quicklime water, with 100 kilograms per mu. If lobsters are raised in old ponds or lakes, silt should be cleared, trimmed and exposed. 10-15 days before stocking shrimp seedlings, 50 kilograms of quicklime per mu should be used for dry pond disinfection. At the same time, completely eliminate the predatory wild enemies such as catfish, Loach, black fish, snakes and rats in the pond. 10-15 days before stocking, 100-200 kg of fully mature manure such as pig manure is applied per mu of water to cultivate plankton and provide appropriate amount of organic detritus as shrimp feed. Before the pond enters the water, it is best to install a water barrier net of 60-80 mesh to prevent the enemy from entering the water. The depth of the pool water is maintained at 50-80 cm and the transparency is between 30-40 cm.

Stocking of Shrimp seedlings

Before stocking, clear the pond with quicklime 100~150kg/ mu to kill harmful fish and harmful aquatic insects in the pond and avoid enemy attacks. After 3 days of disinfection, water was fed, and 10 days later, 300~500kg/ mu was used to ferment mature organic fertilizer and water to cultivate rich plankton and provide sufficient bait for shrimp seedlings.

The stocking shrimp seedlings generally choose the shrimp seedlings with body length 3~5cm, strong physique and no disease, and the stocking density can be controlled at 2000,000,000 pieces / mu. The stocking density of shrimp seedlings can be appropriately increased. Because the shrimp is strong and bully, the small is afraid of the big, so the seedling specifications of the same pond should be neat. Avoid excessive difference in water temperature when releasing seedlings, and it is appropriate to go into the pool in the evening or dawn. Before releasing the seedlings, slowly add a small amount of pool water to the seedling transport container until the container water temperature is close to the pool water temperature, and then gently pour the shrimp seedlings into the pool water.

Stocking shrimp seedlings should be carried out on sunny mornings and evenings with 6000-8000 young shrimp of 2 cm long or 4000-6000 young shrimp of 3-5 cm long per mu. The specifications of shrimp fry released in the same pond are neat and consistent. At the same time, it can raise about 50 grams of flowers, 300-400 silver carp and 200 mackerel in pond water.

Minced fish and minced meat should be used within 3 days after stocking, and minced fish, minced meat or formula feed should be put in 1 month after 3 days. When the shrimp fry grows to 6-7 cm, all the minced snails, mussels and appropriate amount of plant feed such as wheat, wheat bran, corn, cake or formula feed can be fed. The daily feeding amount is based on full, finished and no residual bait. Generally, crayfish are fed at 15% of body weight and adult shrimp at 5% of body weight, which can be adjusted according to the eating condition of shrimp. Feed twice a day, once in the morning and once in the evening, and the evening feed accounts for 70% of the daily feed. The bait should be placed around the pond and dispersed appropriately, and more lobsters should be thrown in places where lobsters are concentrated to facilitate their feeding.

Feeding and management

1. Bait feeding

Freshwater lobster is omnivorous. It likes not only animal bait such as fresh miscellaneous fish, snail clam, earthworm and viscera of livestock and poultry, but also plant bait such as soybean, bean cake, wheat bran, corn and fresh aquatic grass. It can also be fed with compound feed for shrimp. It can be seen that the bait problem of freshwater lobster is easy to solve. According to general experience, the amount of bait given throughout the day should be based on eating, eating, and leaving no residual bait. At present, the best aphrodisiac for shrimp is 20-25% of body weight, 15-20% of body weight for prawns, and 10-15% of body weight for prawns. Feed twice a day, once in the morning and evening. Because freshwater lobsters mainly eat at night, 70-80% of the whole-day bait is fed at night, and the bait should be put in the shallow water by the pool. Feeding should be timed, fixed, quantitative and qualitative. Each pond can set up a 2-4 bait observation table to observe whether the bait is finished every morning to determine the amount of bait at that time. Too little feeding will inhibit the growth of lobster or kill each other because of hunger. Too much will not only increase the cost but also cause the pond environment to deteriorate, which is disadvantageous to the growth and shelling of the lobster. Bait can use general shrimp bait or lobster special bait.

2. Water quality management

Pool water requires fresh water quality, transparency 30~40cm, PH value 7: 9, dissolved oxygen greater than 4g/L. In the process of culture, attention should be paid to the water quality and the environment at the bottom of the pond so as not to worsen it. When the dissolved oxygen content in the water is very low, the water quality deteriorates, or when the thunderstorm, muggy days, continuous cloudy days and other bad weather, bait should be reduced or stopped. When the weather is too cold or too hot, the pool water can be properly deepened in order to prevent the extreme temperature to stabilize the bottom water temperature. In the high temperature season from June to August, the water is changed every 5-7 days, each time the amount of water is 20-30% of the pool water. If it is inconvenient to change water, you can add new water regularly.

3. Disease control

Should inspect and patrol the pond frequently, and pay attention to the lobster's foraging, activity, growth and molting, so as to take necessary technical measures in time. Remove the moss in the pond in time; often check the filter screen at the inlet and outlet to prevent the escape of lobster or the entry of wild fish and other pests due to broken filter. Always pay attention to whether there are enemy creatures in the pond, such as water rats, water snakes, water birds, etc., and if so, they should be removed in time. Shrimp seedlings should carry out body surface disinfection before going into the pond to prevent pathogens from being brought into the pond, regularly disinfect shrimp ponds with quicklime, often add new water to keep the pond water clean, and add a variety of vitamins to shrimp feed to enhance shrimp immunity.

Freshwater lobster has stronger disease resistance than river crab, green shrimp and other aquatic products, but under the condition of artificial culture, its disease prevention and control should not be taken lightly. Adult shrimp or young shrimp must be disinfected before entering the pond to strictly prevent pathogens from being brought into the pond. During the normal feeding period, the water body was disinfected regularly, mainly quicklime, and the whole pool was sprinkled with quicklime 10~15kg/ mu dissolved water every 15 days, which not only played the purpose of disease prevention and treatment, but also conducive to the shelling of freshwater lobster. In the summer high temperature season, multivitamin, calcium tablets and other drugs are added to the diet every 15 days to enhance the immunity of freshwater lobster. Pay attention to patrolling the pool every day to achieve early disease detection, early prevention and early treatment.

Fishing harvest

It is generally raised for about 2 months, and when the lobster weighs more than 50 grams, it can be caught on the market. Lobsters are caught in shrimp cages, ground cages, purse seine and other methods. Freshwater lobster grows fast, can be harvested and listed in the same year, and can be harvested by net or dry fishing. Net catch: as the lobster is mainly foraging at night, the net can be placed in the shallow water by the pool before dusk, the tail of the net leaks out of the water, and the shrimp can be collected the next morning. Dry capture: after repeated net capture, the pool water is drained at last, and the net is copied and caught. If the aquaculture output is more, and a large number of products are listed in stages and batches, fishing with nets such as trawling or casting nets can also be taken. It is better to harvest when the night is dark.

Problems related to lobster culture

With the continuous heating up of the "lobster fever", the "lobster culture fever" is also heating up year by year in recent years. However, most employees are affected by the traditional concepts such as "lobster culture" and so on. Ignoring the correct management of water quality, culture environment, feeding, disease control and other aspects in the culture process, leading to the failure of most culture. At the same time, the "breeding fever" also gives those with a bad state of mind and speculators the opportunity to swindle money wantonly. Last year's "Dragon King 811" is the most typical case in recent years. For this reason, according to the results of my experiments in this project over the years, I would like to give the following advice to those who want to engage in lobster farming:

1. Yield per mu: the yield per mu of lobster is closely related to stocking density, culture environment, feeding amount, disease control and so on. Usually from April to May, there are about 15 seedlings / jin per mu and 60-100 jin of seedlings per mu, and the output of the year is about 450 jin. The output of the year is about 450 jin. The annual output is about 550 jin. Exaggerate too much than this output, remind everyone to pay attention! Be careful to be fooled! The amount of input can be increased appropriately if the culture environment is good.

2. Seedling: the crayfish we are talking about are all crayfish or Japanese crayfish, and they are all of the same breed. The so-called "hybrid breed" is still in the experimental stage and can not be trusted. The only difference is between trained seedlings and natural seedlings. Artificially propagated seedlings stay in the laboratory stage because of the high cost and the abundant and cheap natural seedlings at present. It is said that artificial seedlings can not be trusted! After training, the general survival rate of seedlings is about 85%, and the survival rate of natural seedlings is not higher than 60%, and it is also related to the water area. It is generally recommended to choose seedlings in the same water area, the survival rate can be guaranteed!

3. Culture environment: select ponds with good water sources. The coverage of aquatic plants in the ponds should be 30-60%. It is best to mix floating aquatic plants (such as water peanuts) and bottom aquatic plants (such as withered grass, etc.). The transparency of the water body is about 30 centimeters. The idea that lobsters can be raised in both good and bad water is incorrect!

4. Feed: although the lobster is omnivorous, whether its growth is good or not depends on the intake of protein. It can be fed mainly with fresh miscellaneous fish and field snails, supplemented by plant bait, or fed with compound feed with a protein content of not less than 32%. Rotten animal and plant feed is not suitable for feeding, because of its low utilization rate and easy to deteriorate the water quality, and should not be fed!

5. Disease prevention and control: if breeding is to be successful, disease control is also very important. We must get out of the misunderstanding that "lobsters will not get sick" and disinfect them regularly. If the PH value in the water is less than 7, every 15-20 days, the quicklime with the final concentration of 20 grams per cubic body of water shall be evenly sprinkled after pulping. In general, ponds are disinfected with drugs every 15-20 days, and molt-stimulating hormone is added to the feed every 15 days or so for three consecutive days.