In recent years, artificial breeding of crayfish has begun in many areas of China, but the yields vary widely, with high yields of 400-500 kilograms per mu and only tens of kilograms low. To raise the survival rate of aquaculture and obtain high quality and high yield, we must master the following major technical measures.
1, a reasonable breeding density
Maintaining a reasonable culture density will not only be conducive to the full utilization of the productivity of the ponds, but also increase the yield, size, and economic benefits of the shrimp. If unilaterally pursuing production and raising the density of farming, it will increase the difficulty of aquaculture management, and crayfish will also fight for survival space and kill each other. The large amount of bait and excrement produced by high-density culture will also deteriorate the water quality, further reducing the living space for crayfish. The environment of the pond has a greater impact on the excavation of crayfish. Under the condition that the water quality is richer, the bottom silt is more, and the organic matter is rich, the caves are reduced, and the crayfish can also kill each other. Generally speaking, the reasonable breeding density of single-caught crayfish in ponds is: 3-40 thousand larvae with a size of 2-4 cm per acre in the spring (February to February); summer (July-August) Instead of serving juvenile shrimps, we must deliver quality crayfish broodstock, with 20-25 kg of water per acre, and a ratio of 3:1 for males to females. In the fall (September-October), the juvenile shrimps that have just left the mother's body should be released. 10-12 mm) 350,000-50 thousand tails.
2, stocking specifications should be basically the same
When stocking crayfish, it should be noted that the stocking specifications cannot differ too much. Otherwise, stocks of large, medium and small sizes must be stocked. In the growing process, we must also pay attention to the specifications of the crayfish. If the sizes are different, the phenomenon of prawns eating shrimp will occur, and the survival rate will be greatly reduced, affecting the increase of aquaculture production.
3, correctly feeding
The feeding of crayfish is the key to feeding. When feeding, attention should be paid to the types of food, the palatability of the feed, the determination of the amount of feed, the feeding method of the feed, and the feeding time of the feed. Crayfish are omnivorous animals, animal feed and plant foods can feed. In the aquaculture production, some animal feedstuffs such as cereals, grassy food and live snails are usually fed. Crayfish are bulimia. Insufficient feeding will not only affect the normal growth of crayfish, but also the phenomenon of self-inflicted, so we must ensure that crayfish can feed enough food and the food is fresh. Improper feeding or improper feeding methods can result in wastage of food and water quality. In general, the amount of bait is calculated according to the body weight of shrimp ponds. During the peak season (April-September), the amount fed is 7%-8% of the body weight of shrimps, and the remaining season is 1%-3% of the body weight of shrimps. When the actual feeding is performed, it is necessary to adjust the feeding amount flexibly according to specific conditions such as weather conditions, water quality, the amount of aquatic plants in the pond, and the amount of remaining feed. Crayfish have a habit of nocturnal outbreaks. They often come out for activities and feed during the night. They usually inhabit the water grasses during the day. Therefore, about 90% of the total amount of bait is generally fed at about 9:00, and about 70%-80% is added at about 17:00.
4, timely improve water quality
Natural crayfish often live in stinking ditch, and many farmers mistakenly believe that crayfish have strong anti-fouling ability and can survive under poor water quality and environmental conditions. In fact, poor water quality can reduce the physiology and vitality of crayfish. In the crayfish culture process, it is necessary to maintain a water clarity of 30-40 cm, a pH of 7.5-8.5, and a dissolved oxygen of 3 mg/l or more. To this end, we must strengthen water quality management, often adding new water, and regularly pouring lime slurry on a regular basis (every 15-20 days) at a rate of 3-5 grams per cubic meter of water to regulate water quality and increase ionized calcium content in water. Shrimp oysters need calcium when growing. Once pool water is aging, it should be replaced in time to keep the pool water “fat, live, tender, and cool†and promote the growth of crayfish in time. When the water temperature is appropriate and the feed is sufficient, generally 60-90 days of juvenile shrimp can reach commercial specifications of about 20 grams per tail.
5, increase the hidden objects
Crawfish is ferocious and has a strong habit of occupying land. When there are not enough caves and plants for concealment or concealment, self-mutilation is extremely serious. Using crayfish like burrowing habits, the establishment of artificial caves can effectively prevent crayfish from killing each other. The artificial cave can be built on a slope below the water level, with a diameter of 6-10 cm and a depth of 15-30 cm. Crayfish also have the habit of clumping aquatic plants. Planting or placing water peanuts, black algae, water hyacinths, pot seeds, and water lettuces in the rearing ponds can provide concealment for crayfish and increase their living space. Reduce mutual killings. At the same time, aquatic plants can also be used as food for crayfish to reduce the consumption of artificial feed and save the cost of farming.
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