Culture techniques of freshwater crabs

Before and after the Mid-Autumn Festival is the best time to eat crabs, think about it, but the price of high-quality hairy crabs is not low, eating crabs to improve life is a good choice, but with people's living standards getting higher and higher, the pursuit of quality is also getting higher and higher, so crab farmers should pay attention to learn breeding techniques, in our daily life, in fact, the most often seen is freshwater crabs. Because freshwater crabs are easier to raise in large quantities than other crabs, there are more in the market.

Culture techniques of freshwater crabs

First, buckle crab breeding

In order to improve the survival rate of young crabs and increase economic benefits, we must first cultivate buckle crabs. In order to achieve commercial crabs, most of them use temporary culture technology in plastic greenhouse. Choose ponds with good water quality and adequate water sources, the area should not be too large, the water depth should not exceed 1.2 meters, the pond shape should be east-west, and the sun is sufficient.

1. Release seedlings. 15-20 days before the release of crab seedlings, sprinkle and disinfect with 75 kilograms of quicklime per mu. After the medicine disappears, enter water with 80-mesh filter, cultivate basic bait, transplant aquatic plants (must be strictly sterilized), and set up necessary anti-escape facilities. Crab seedlings can be shallower when entering the pond. It is beneficial to improve the water temperature and the growth of algae and aquatic plants in the water.

2. Feeding. Feed 2 to 3 times a day, soybean milk, fish, shrimp, etc., should be cast in the surrounding shallow areas, bait calculated according to 4% of body weight, and always pay attention to weather, water sanctions, individual growth, depending on the number of bait creatures. With the growth of young crabs, high-quality aquatic plants such as duckweed should also be increased.

3. Water quality. Pay attention to the regulation of water quality in daily management, grasp the fat and cool water quality, change water frequently and rarely, so as not to cause drastic changes in water temperature and water level. After about 2 months of cultivation, the buckle crab can be achieved.

2. Adult crab culture

Adult crabs like the water environment with clean water quality and greater transparency, with numerous water plants and rich bait, and the river crab is the most suitable for growth, mostly in ponds, lakes, river swings and rice fields.

1. Pond conditions

The crab near the meatball has sufficient water source, convenient entry and drainage, good water quality and no pollution. Choose clay, sandy soil or sub-sandy soil with good ventilation, which is conducive to the growth and reproduction of aquatic plants and benthic insects, snail clams and water earthworms. The old pond should clear silt thoroughly, 10cm at the shallowest point, and several mounds slightly above the water surface can be made in the pond, that is, crab island, where aquatic plants can be transplanted. The pond should not be too steep, and the slope ratio is generally less than 1.50. Otherwise, the pond should not be too steep. River crabs are easy to dig holes and are not conducive to climbing out of the water at night. Artificial caves can also be built.

2. Transplant aquatic plants

The natural yield of river crab mainly depends on the number of aquatic plants and benthos (bait organisms) in the water area. It is an indispensable technical measure to plant aquatic plants in the process of breeding. In addition to supplying vitamins for crabs, people often say, "crab size, look at aquatic plants."

3. Escape prevention facilities

Escape prevention facilities mostly use plastic film, but also use cement board, depending on their respective conditions.

4. Clear the pond and disinfect

Portunus trituberculatus is generally disinfected with quicklime in the first half of the month before seedling release, with a dosage of 75 kg per mu. On the one hand, it can kill enemy organisms, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in water, and promote the molting growth of river crabs. Fertilize in time after receiving water, cultivate algae and basic bait, transparency is generally maintained in 40~50cm, if tadpoles or frog eggs are found to be removed in time, so as not to compete for food and harm young crabs.

5. Release seedlings

In the selection and purchase of seedlings, the crab seedlings produced in the Yangtze River system are the best, with neat specifications, complete steps, strong physique, active crawling, no injury and no disease.

Seedling release and density, pay attention to temperature difference when releasing seedlings. The seedlings purchased from other places should be soaked in water for 2-3 minutes, taken out and placed for 10 minutes, and repeated for 2-3 times. After the young crabs gradually absorb enough water and adapt to the water temperature, the survival rate can be improved.

6. Density: most of them are mixed culture, especially the mixed culture of fish, shrimp and crabs, the economic benefit will be higher. The density can be controlled within 1500 / mu and the specification is 120-150 buckle crabs. If the conditions are poor or shrimp culture can appropriately reduce the amount of seedlings.

Living environment of freshwater crabs

1. Crabs can live on wood or other floating objects, and many species live together with other animal camps.

2. A small number of crabs grow and breed completely in fresh water, and most of them live under the rocks of mountain streams.

3. The family Cryptophagidae lives in a capsule formed by reef-building corals. Female crabs are trapped in the sac for life after mating, and the hatched larvae can escape through unclosed pores.

4. Bean crabs often sneak into the mantle cavities of some mollusks or in the ducts of hairy animals.

5. A small number of crabs, such as ground crabs, can adapt to life on land, live in wet mud holes, migrate to the sea during the breeding period, and most of the crabs are omnivorous.

Morphological characteristics of freshwater crab

Freshwater crab head breastplate developed, abdominal degeneration, commonly known as "navel", male pointed navel, female navel. Just like the ink is divided into six colors and the piano has seven notes, the crab also has many flavors: crab meat, crab paste, crab roe and crab meat.

The difference between freshwater crab and sea crab

The main results are as follows: 1. The back shell of freshwater crab is round and the sea crab is fusiform.

2. Sea crabs can be used both dead and alive, while freshwater crabs can only be eaten alive.

3. The fresh and energetic river crab shell has luster, strong claw force, smooth legs, complete and solid legs, crawling fast, and its slight spitting sound can be heard when quiet. It is best to raise freshwater crabs in clean water for some time before eating, so that they can spit out the dirt in their abdomen and then remove the crab stomach and cook cooked food.

4. The market time of freshwater crab is different from that of sea crab. Sea crabs have been on the market for a long time, from April to October. Freshwater crabs come to market later and shorter than sea crabs, usually from July to October.

There are many kinds of crabs, the price of each kind of crab is different, the taste is also different, and the breeding technology of each kind of crab is different, raising crabs should pay attention to some problems that we need to study hard. So farmers have to decide what species to breed according to the market in order to maximize profits.