River crab breeding is an important step in the production of river crabs. Cultivating robust young crab seedlings is conducive to high and efficient crab production. If big-eyed river crab larvae are directly put into adult crab pools, not only will the temperature in early spring be low and the crab seedlings will not survive, but they will also often kill each other due to lack of food, resulting in a low survival rate. Plastic greenhouses need to be built to raise crab seedlings from March to May. According to the biological characteristics of the young crabs, environmental conditions and sufficient bait are provided for their growth and shelling, so as to cultivate five species of crabs with neat specifications, appropriate size and high survival rate. Young crabs.

1. Build a shed and build a pool. The river crab nursery pond depends on the number of crabs, usually 0.5-1 mu. The pool depth is 0.8-1 meters, the water depth is 0.4-0.8 meters, and the pool slope ratio is about 1:1.5. The water source is abundant and the water quality is good. The bottom of the pool is hard and the ridge is solid and water-proof. The plane of the bottom of the pool is inclined toward the water outlet. The pond is rectangular, arranged east-west, with an aspect ratio of 5:3.

2. Clean and disinfect the pool. Cleaning the pool can kill harmful creatures in the pool. Before stocking crab seedlings, the mud in the nursery pond must be removed and holes and cracks must be filled. Newly built crab ponds or crab ponds renovated from fish ponds must be disinfected with pool cleaning drugs before stocking. Pool cleaning drugs mainly include bleaching powder, etc. How to use bleaching powder to clean the pool: first calculate the volume of the pool water, and use 20 grams of bleaching powder (20ppm) per cubic meter of water. Dissolve the bleaching powder required for the nursery pool with water, and then splash it all over the pool immediately. Usually crabs can be stocked 5 days after cleaning the pool. Seedling. Note that the water in ponds built in saline-alkali land is highly alkaline and has a high pH value, so quicklime with strong alkalinity cannot be used as pond clearing medicine.

3. Receive and transport crab seedlings. To ensure that "people wait for seedlings, cars wait for seedlings, and ponds wait for seedlings", after the crab seedlings are transported to the pond entrance, the crab seedling box should be put into the pond water for 2 minutes, then lifted up, and repeated 2-3 times to make the crab seedlings wait for seedlings. The seedlings adapt to the water temperature and quality of the pond, and then are placed in the cage for temporary cultivation. After the crab seedlings are placed in the cage, the live crab seedlings will automatically swim out and then be removed from the cage. After the crab seedlings move normally, feed the water fleas with medicine.

4. Stocking density. Generally, 80-150 crab seedlings (5-10 kg) are stocked per acre. If the specifications are large and the quality is good, the density can be thinner, otherwise it can be denser.

5. Plant aquatic plants. When planting water peanuts, duckweed, and Vallisneria, you must first rinse the water peanuts, duckweed, and Vallisneria with river water to remove most of the attached shrimp seeds and fish eggs, and then disinfect them with 20 ppm potassium permanganate solution. Bacteria can be used to purify water quality, and water peanuts, duckweed and Vallisneria can be used as habitats and bait for young crabs. Plastic greenhouses have played a great role in vegetable cultivation and rice seedling cultivation. However, the application and promotion of plastic greenhouses in river crab breeding is rarely known. The author has figured out a method to temporarily raise river crabs by increasing the temperature in winter. Its operation and application are as follows:

1. Construction of greenhouse.

Having sufficient, fresh, clean water sources without pollution from pesticides and chemical wastewater is a prerequisite for the temporary cultivation of river crabs. Greenhouses should generally be built beside rivers, lakes or large ponds, and well water can also be used (but must have oxygenation equipment).

The temporary breeding pond is built into a rectangular shape, oriented east-west, 4-10 meters long, 10-100 meters wide, and 1-1.2 meters deep. The dam and bottom are compacted to prevent water leakage and water collapse. Larger ponds should be equipped with inflatable pipes, and an air pump should be used to inflate from outside when raising. To facilitate capture and management, the bottom of the pond can be covered with polyethylene mesh. Use soil, bricks, wooden piles, bamboo poles, iron wire or laminate strips to fix the agricultural film and build a greenhouse. The greenhouse can be built in a slope shape (the slope faces the south) or in an arch shape. Depending on the size and shape of the greenhouse, leave doors at both ends and sides for feeding and daily management.

After the pond is built, use quicklime, bleaching powder, tea meal, croton and other drugs for disinfection. Add or plant an appropriate amount of aquatic plants that are easy to survive and do not decay for crabs to live in. Put it into 0.5-1 meter deep water, and after the medicinal properties disappear, you can put in the optional river crabs.

2. The choice of crab preparation.

Choosing the right river crabs for breeding is one of the keys to the success of greenhouse temporary breeding. It is best to select river crabs of the same species, with similar specifications (usually only weighing 50-100 grams), strong physique, and free of diseases and limbs. The most important thing is to select autumn-old crabs whose glands have not yet matured.

If the proportion of sexually mature crabs reaches more than 30%, the temporary breeding value will be lost.

It is best to disinfect the selected river crabs. The available drugs include bleaching powder, formalin, potassium permanganate, etc. After disinfection, the crabs can be put into the greenhouse for feeding.

The stocking density is 2-5 per square meter.

3. Feeding.

The use of plastic greenhouses in winter can keep the water temperature in the greenhouse above 15°C during most of the winter, ensuring that river crabs can grow normally under suitable water temperatures. When the water temperature drops below 18°C, the feeding intensity of river crabs is significantly reduced, but the greenhouse ensures that river crabs survive the winter safely. River crabs can be cultivated in the greenhouse for 3-5 months.

River crabs are fed in the greenhouse, mainly to continue their growth in the early stage, and in the later stage to promote their gonad development, accumulate nutrients, and improve their quality for sale on the market. Therefore, the types of feed and feeding methods are also different during these two stages.

In the previous stage of feeding (from November to one and a half months before going on the market), the bait should be mainly plant food. Such as soaked or cooked wheat grains, soybeans, sweet potatoes, vegetables, etc. The daily feed amount accounts for about 5%-8% of the crab weight, and is fed once in the morning and afternoon. Feeding at 10-11 am, accounting for 3 parts of the bait, and feeding at 4-5 pm, accounting for 7 parts. .

In the later stage of feeding, the animal protein content in the food should be appropriately increased. Small miscellaneous fish and shrimp, silkworm chrysalis, snail meat, compound feed, etc. can be fed in appropriate amounts. However, in order to reduce costs, or animal-based When feed is not easy to obtain, you can still feed it according to the above method, and the effect is better.

4. Daily management.

The key to successful temporary cultivation of river crabs in plastic greenhouses in winter is to select the crab species to be raised and maintain a high water temperature to ensure good water quality.

In order to maintain the water temperature, attention must be paid to the sealing between the plastic film and the edge of the pond. Do not open the greenhouse door for a long time or frequently. If the agricultural film is damaged, repair it in time. If you encounter heavy snow occasionally, the snow on the greenhouse should be cleared away in time. It is also necessary to flexibly adjust the depth of the water body according to weather conditions. When there is sufficient sunlight, the water depth can be reduced to help increase the water temperature quickly; in continuously low temperatures or cloudy weather, water should be added until the pool is full.

Because the pond space is small, the stocking density is high, there is a lot of bait, and the water temperature is relatively high, the leftover bait and excrement of river crabs are easy to decay, causing the breeding of pathogenic organisms. Therefore, attention should be paid to observing the crab's feeding situation every day and adjusting the feeding amount at any time. At the same time, depending on the water quality, change 1/5-1/3 of the water in the pool every 1-3 days when the weather is warm in the afternoon. Water changes should be carried out slowly, with water in and out at two opposite corners of the pond at the same time, which facilitates water exchange without causing drastic changes in water temperature.

In order to prevent diseases, appropriate amounts of sulfonamides and antibiotics should be mixed in the feed every 1-2 weeks. The feed can be soaked in a liquid prepared with a prescribed dose of medicine and then fed together with a small amount of remaining liquid. If disease occurs, timely treatment should be carried out and dead crabs should be fished out of the pool. It is also necessary to prevent rats, snakes and other harmful organisms from entering the greenhouse and causing harm. 1. Yangcheng Lake Hairy Crab

This crab is produced in Yangcheng Lake in Suzhou, Jiangsu Province. It is a famous Chinese product well-known at home and abroad, and is also the first Chinese well-known trademark of aquatic products in China. Yangcheng Lake hairy crabs have always been known as the crown of crabs. Yangcheng Lake has rippling blue waves, as pure as a mirror, deep water and hard bottom, abundant aquatic plants, wide extension and pleasant climate. It is the most ideal "Crystal Palace" for crabs to settle and grow. The hairy crabs produced at Lotus Island in Yangcheng Lake are authentic Chinese mitten crabs from the Yangtze River. Due to the excellent ecology of the waters, the crabs produced in Yangcheng Lake have the characteristics of crispy shells, firm faces, plump limbs and muscles, and large individuals.

2. Gucheng Lake Hairy Crab

This crab is produced in Gucheng Lake, Gaochun District, Jiangsu Province. The water area of ??Gucheng Lake is hundreds of miles in diameter, with rippling blue waves, luxuriant aquatic plants, and wide extension. The crabs grown here are particularly distinctive in shape and meat quality among the crab family. Their meat is tender, delicious, and rich in nutrients. Each 100 grams of Gucheng Lake crab meat contains 14 grams of protein, 13 mg of iron, 0.71 mg of riboflavin, and 5960 international units of vitamin A. In the early years of the Republic of China, Shi Jinmo, one of the four famous doctors in Beijing, once compared the crabs of Gucheng Lake to the number one crab in the world.

3. Liangzihu Hairy Crabs

Liangzihu Hairy Crabs in Ezhou City, Hubei Province, fully ecologically cultured, products with origin mark. “Throughout the ages, the poetry of Jiangxia has existed, and the crabs on the shores of Liangzi Lake are getting fat.” The year before last, Yu Qiuyu composed an impromptu poem on the spot at the opening ceremony of the cultural festival, which made Liangzi Lake crabs famous. Liangzi Lake is the second largest lake in Hubei Province, with two-thirds of its water surface located in Jiangxia District. The lake water is clear and the water quality reaches the second grade standard. The crabs produced are large, with white belly, fresh meat and delicious taste.

In 2004, the "Liangzi" brand Liangzi Lake river crab was awarded the product of protected origin, and its trademarks were successively awarded the title of "Famous Trademark of Hubei Province". The products are favored by consumers and are sold nationwide and exported to 7 countries and regions including South Korea, Japan, Singapore, Malaysia, Hong Kong, Macao and Taiwan, with annual foreign exchange earnings of US$5 million. Liangzi Lake is one of the freshwater lakes with the largest water capacity in Hubei Province and the second largest lake area in the province. It is the hometown of the famous Wuchang fish both at home and abroad. The area for raising crabs in Liangzi Lake is nearly six times that of Yangcheng Lake in Suzhou, its output is twice that of Yangcheng Lake, and its water quality reaches the national Class 2 standard. Coming to Liangzi Lake to eat crabs is a must.

4. Tianjin purple crab

This is a kind of Chinese mitten crab. It is small, only about the size of a coat button. When you open the lid of the crab, you will see that the crab roe is purple in color and turns orange when cooked. It is extremely delicious. Purple crabs are produced in the cold and windy winter, so they are often used in assorted hotpots.

5. Laizhou crab

This crab is a famous specialty of Ye County. Because Ye County was the seat of Laizhou Prefecture in ancient times, the name Laizhou Big Crab has been passed down to this day. There are three raised parts on the back of the Laizhou crab, and there are 9 serrations on each front edge. The last tooth is particularly long and resembles a shuttle, so it is commonly known as the "three-tuberculated swimming crab". This kind of crab is large in size, fresh in taste and tender in texture. The largest female crab weighs 0.75 kilograms. The egg masses of the female crab, the fat of the male crab, the white and tender muscles in the claws and the meat on the hind legs of the big crab taste even more delicious and unforgettable.

6. Swimming Crab

Liaoning Xingcheng Swimming Crab: This crab’s meat is white in color, tender in texture, creamy like gelatin, and delicious in taste. It is the top-grade sea crab.

7. Nanhu Crab

This crab is produced in the Hangzhou, Jiazhou and Hushui areas of Zhejiang Province. It is famous for its large size and delicious meat. The lake crabs here used to reproduce naturally and were caught and marketed every year during the flood season. Artificial breeding and stocking have begun, and certain results have been achieved.

8. Junshan Lake hairy crabs

Junshan Lake clear water hairy crabs are famous for their “green backs and white bellies, golden claws and yellow hairs, large individuals, delicious taste and tenderness”, and are well-known in China. A famous aquatic product brand, it is also the winner of the previous Poyang Lake Crab King and Crab Queen. At the 2004 Chinese mitten crab exhibition evaluation meeting in the Yangtze River system, the "Junshan Lake" crab defeated Jiangsu's "Yangcheng Lake" and won four crowns including king crab and queen crab among eight awards. Thousands of tons of crabs come out of Junshan Lake every year and flow continuously to the dining tables of citizens in Nanchang, Hangzhou, Hong Kong and other domestic cities. They are not only sold well domestically, but also exported to Japan, Southeast Asia and other countries and regions.

9. Minquan County Qiushui Lake Crab

Minquan River Crab is pure natural, original ecological, pollution-free, high quality, large and fleshy, with yellow hair, golden claws and yellow fat, fragrant and delicious. Rich in nutrients. It was named the "Hometown of River Crabs in China" by the China Fisheries Association and is well-known in cities such as Beijing, Shanghai, Changzhou, Suzhou, Xi'an, Wuhan, Tianjin, and Zhengzhou. It has been exported to South Korea; in 2002, it won the gold medal at the China (Shangqiu) Agricultural Products Expo, and in 2004, it won the gold medal at the first aquatic products in China (Zhengzhou). Minquan County has been designated and awarded as "Key Fishery County in Henan Province", "River Crab Breeding Base in Henan Province", "Advanced County in Aquatic Products in Henan Province", "Healthy Breeding Demonstration Base of the Ministry of Agriculture", "Pollution-free Breeding of Aquatic Products in Henan Province" base".