What kinds of freshwater crabs are there?
Freshwater crabs
1, hairy crab
The scientific name of hairy crab is Eriocheir sinensis, which is called river crab in the north and hairy crab in the Yangtze River basin. It exists in rivers, lakes and streams from Henan to the Pearl River in northern China. Hairy crabs in the Yangtze River system are representative species in southern China because of their wide distribution and high yield. The famous crabs are Yangcheng Lake hairy crabs and hairy crabs produced in Yangcheng Lake, which are very famous freshwater crabs with green back, white belly, golden claws and yellow hair. They are called "the king of crabs". At present, rice and crab species are cultivated together in many places in China, forming some brand products of crab rice.
2. blue crab
The blue crab, also known as the saw-edged blue crab, has a hard, oval shell, looks a little flat, a strong chest and hard claws, similar to scorpions, so some people call it scorpions. Blue crabs like to inhabit mudflats in intertidal zones, mangroves and swamps, and are widely distributed in China, mainly in coastal areas such as Zhejiang, Guangdong, Guangxi and Fujian, especially in Jiangsu and Zhejiang. The most famous blue crab is a specialty of Sanmen County, Zhejiang Province, which is a symbolic product of chinese national geography.
3. Zhexie Longbei
Stone crab, also known as crab and crab, is a kind of freshwater crab. It mainly lives under rocks in mountain streams, or in grass and mud on both sides of streams, and also burrows along rivers, lakes and ditches, and is distributed in other provinces except Xinjiang, Qinghai, Inner Mongolia and Northeast China. There are many kinds of crabs, among which the most famous are Sinopotamon sinensis, Sinopotamon Zu Mao, Sinopotamon serrata, Sinopotamon hainanensis, Sinopotamon purpurea and Sinopotamon Sichuan. The crab meat of the stone crab is full of flavor, the crab paste is surging and the taste is excellent.
4. water crab
The appearance of water crab is actually a stage in the growth of blue crab. The newly molted crab is in a soft state and is called "soft-shelled crab". At this time, because the soft-shelled crab lies on the bottom of the water, it will absorb a lot of water, which will lead to the relaxation of the crab. After 3-4 days, the new shell will completely harden. This kind of shell will change from soft to hard, which will increase the water content in the crab and double its weight. Therefore, it is named water crab, which grows in the fresh water area of Yu Xian with its juice.
5. Hairy crabs
Eriocheir sinensis, also known as Eriocheir sinensis, Eriocheir sinensis and Eriocheir sinensis, is the most abundant freshwater crab in China. Hairy crabs are favored by consumers at home and abroad because of their rich nutrition and delicious meat. Eriocheir sinensis has become the main breeding species in various places, and the breeding industry of Eriocheir sinensis has changed from "raising crabs" in pursuit of yield to "raising crabs and raising ecological crabs" with quality and benefit as the center.
6. rice crab
Rice crabs are actually river crabs and hairy crabs. Nowadays, river crabs are cultivated in rice fields in many areas, so they are named rice crabs. Paddy crabs mainly feed on aquatic plants, humus, snails, mussels, worms, insects, small fish and shrimp.
Development: freshwater crab culture technology
1, crab culture
In order to improve the survival rate of young crabs and increase economic benefits, Eriocheir sinensis should be cultivated first. In order to realize commercial crabs, most of them adopt temporary rearing technology in plastic greenhouses. Choose a pond with good water quality and sufficient water resources, the area should not be too large, the water depth should not exceed1.2m, the east-west direction of the pond is good, and the sunshine is sufficient.
(1) release the seedlings. 15 ~ 20 days before the crab seedlings are released, 75 kilograms of quicklime should be sprinkled on each mu for disinfection. After the medicinal properties disappear, it is necessary to feed water with an 80-mesh sieve to cultivate basic bait, transplant aquatic plants (which must be strictly disinfected), and set up necessary escape prevention facilities. Crab seedlings can be shallower when they enter the pool. Conducive to improving the water temperature and the growth of algae and aquatic plants in the water.
(2) feeding. Feed bait 2 ~ 3 times a day, such as soybean milk, fish, shrimp paste, etc. , and feed in the surrounding shallow waters, and feed at 4% of the body weight, and always pay attention to the weather, water quality sanctions, individual growth, and the number of organisms competing for food. With the growth of young crabs, high-quality aquatic plants such as duckweed should also be added.
(3) water quality. Pay attention to water quality regulation in daily management, grasp the water quality, change frequently and change less, so as not to cause drastic changes in water temperature and water level. After about 2 months of cultivation, crabs can be detained.
2. Adult crab culture
Adult crabs like the water environment with clean water quality, high transparency, rich aquatic plants and rich bait. The growth of river crabs is most suitable, and they are mostly cultivated in ponds, lakes, rivers and rice fields.
(1) pond conditions
The meatball crab has abundant water resources, convenient water intake and drainage, good water quality and no pollution. Clay, sandy soil or sub-sandy soil are selected, which has good air permeability and is beneficial to the growth and reproduction of aquatic plants, benthic insects, snails and water worms. The old pond should be thoroughly dredged, and the shallowest part is 10cm. Several mounds can be built in the pond, that is, crab island. Aquatic plants can be transplanted on the island, and the pond should not be too steep and have a slope. You can also build artificial caves.
(2) Transplanting aquatic plants
The natural yield of Eriocheir sinensis mainly depends on the number of aquatic plants and benthic organisms (bait organisms) in the waters. In the process of aquaculture, it is an indispensable technical measure to plant aquatic plants well. In addition to feeding vitamins to crabs, people often say that "the size of crabs depends on aquatic plants."
(3) escape prevention facilities
Escape prevention facilities mostly use plastic film, but also useful cement board, depending on their own situation.
(4) pond cleaning and disinfection
Generally, Portunus trituberculatus is disinfected with quicklime half a month before the seedlings are released, and the dosage is 75 kg per mu. On the one hand, it can kill pests, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in the water and promote the molting growth of Eriocheir sinensis. Fertilize in time after receiving water to cultivate algae and basic bait, and the transparency is generally maintained at 40 ~ 50 cm. If tadpoles or frog eggs are found, they should be removed in time to avoid competing for food and endangering young crabs.
(5) releasing seedlings
Crab seedlings produced in the Yangtze River system are the best seed selection, requiring neat specifications, complete steps, strong physique, active crawling and no injuries.
Seeding: Pay attention to the temperature difference when seeding. Fish fry bought from other places should be soaked in water for 2 ~ 3 minutes, fished out and put into the pond for 10 minute, and this is repeated for 2 ~ 3 times. Young crabs gradually absorb enough water, adapt to the water temperature, and then put them into the pond, which can improve the survival rate.
Today's sharing is over. I hope I can help you.