Crayfish is a table delicacy. In summer, crayfish are on the market in large quantities and are extremely popular. However, crayfish in other seasons are rare, mainly because many crayfish are raised in the open air and are not available in spring, autumn and winter. season and therefore rare.
But we know that many cultures can now be raised in greenhouses and can be eaten all year round. So can crayfish be cultured in greenhouses? Let’s find out together.
Can crayfish be cultured in greenhouses?
Crayfish can certainly be cultured in greenhouses.
Crayfish have strong adaptability. In the natural environment, they can survive in temperatures as high as 30 degrees Celsius and as low as 10 degrees Celsius below zero. Crayfish are raised in greenhouses and aquaculture greenhouses, as long as the breeding environment meets the requirements of the crayfish. If the growth environment is good, crayfish can basically be raised.
The main advantage of greenhouses is that they can produce shrimp normally in winter and can make crayfish out of season. Generally, the price of crayfish in winter is 2-3 times higher than the normal market, and the profit is still considerable.
Crayfish greenhouse farming technology
1. Thoroughly clear the pond
Winter shed shrimp farming is a fully enclosed culture. Generally, the pond is dried in September and the pond is The toxic and harmful substances at the bottom should be exposed as thoroughly as possible.
One month before releasing the seedlings, live bacteria can be used to biodegrade the remaining organic matter from the previous shrimp.
2. Control the water level
Before winter shed breeding, increase the pond water level to the highest level at one time under the premise of safety. The best effect is when the water level is about 1m.
Then use fertilizer and water to cultivate algae. The purpose of fertilizer and water is to cultivate a good algae phase. The functions of the algae phase are: first, to increase the dissolved oxygen in the water (about 70% of the oxygen in the water body is provided by algae); The purpose is to absorb harmful substances in the water and purify the water body; the third is to plant aquatic plants. The types of aquatic plants planted are Elodea, Hydrilla verticillata, etc.
The fourth is to pay attention to the changes in algae phase and apply appropriate top dressing at the right time to ensure that freshwater crayfish have sufficient natural food.
3. Larvae management
The shrimp larvae selected for greenhouse culture should first have the characteristics of strong stress resistance, and secondly, they should grow quickly.
It is recommended that farmers with average management level choose shrimp seedlings with stronger adaptability. They should build the frame of the greenhouse in advance before winter. Do not build the roof first, and put out the shrimp seedlings before the water temperature drops. Put them in an open-air overwintering pond and let the shrimp seedlings grow for more than half a month in the natural environment of sunlight and wind. The strong young shrimps are conducive to surviving the winter.
The stocking density is slightly higher than that of summer breeding. There are two reasons for this. First, the water temperature is low and the water quality is not easy to become eutrophic. Second, shrimps in winter sheds can be sold in small sizes.
4. Cover with film
Wait until the water temperature drops below 20℃ before covering with film.
The roof and side sheds are closed every day with an area of ??1/8 to 1/6, and the film is completed in 6-8 days.
This can avoid sudden changes in water temperature and prevent stress reactions in shrimps. The plastic film covering the ground should be tightly pressed with mud bags or mud to prevent water leakage and ventilation.
In the early days of winter, the water temperature is higher than the air temperature. At this time, the greenhouse should not be completely closed, and air inlets and outlets should be left. During the breeding period, if the weather warms up to above 22°C or the temperature inside the shed is too high, the greenhouse should be closed. Open the window or peel off the film appropriately to allow air to circulate and increase the dissolved oxygen content of the pool water under the action of the aerator.
5. Breeding management
In the breeding process, microbial preparations and substrate improvers are mainly used to improve the substrate.
The winter shed is a closed water environment. There is little air exchange in the shed, the oxygen content decreases, and the amount of harmful substances such as nitrite, methane and many decomposition intermediate products increases.
Therefore, in this case, regular detoxification is particularly important.
The air in the shed is not circulating, and 70% of the dissolved oxygen in the water comes from planktonic microorganisms, so special attention must be paid to the construction of excellent algae phase.
When the water temperature is low in winter, the growth and metabolism of shrimp slow down, so the amount of feeding should be reduced to avoid waste and help keep the water clean.
At present, the yield of crayfish cultured in greenhouse farms can reach 1,000 kilograms per mu, while the average yield of crayfish raised outside is only 200 kilograms to 300 kilograms.
Compared with ordinary crayfish, greenhouse-cultured meat is sweeter, more delicious, elastic, and has thin shells. It is favored by the market and has overall considerable economic benefits.