If you make better use of the crab apartment.

In order to make better use of crab apartments to breed/temporarily raise crabs, first of all, the quality of source water must meet the requirements of fishery water quality standards (see appendix), and the factory should be located as close as possible to the water source to facilitate water intake.

I. Temporary feeding/fattening

Temporary rearing/fattening usually refers to a way to temporarily store commercialized crabs or fattened crabs (commonly known as water crabs) to improve fullness and commodity quality, so as to obtain higher prices.

Temporary rearing/fattening has the advantages of simple method, short breeding cycle and quick effect. By temporary rearing, crabs can avoid the time of centralized listing, so as to be sold in time, and at the same time, they can be fattened quickly and improve the quality of crabs.

Temporary rearing/fattening should choose healthy and lively crabs with strong vitality and strong appetite. In order to ensure the survival rate, carefully select one by one, and observe whether the crab shells are clear and tidy in color, free from dirt on the back, complete in appendages, strong and strong, and in good mental state. If you turn the crab upside down, with its abdomen facing the sky, it can be turned back quickly with a strong vitality, but it cannot be turned back. Poor vitality and low survival rate. Then pay attention to the fullness of the crab. Generally, in the same batch of crabs, the body with high fullness is also good.

Crabs sold in the market are generally not recommended because they have been dehydrated for too long.

For parasites and diseases in the body, you can take a few samples to see if the color of the organs is normal and whether there are parasites in the body. If there is, you can't take it.

Regardless of the species of seawater (swimming crab, blue crab) or fresh water crab (Eriocheir sinensis), regardless of specifications, we should pay attention to the three indicators of water temperature, salinity and pH, and the water from crab source and crab apartment should not be too different. The temperature should not exceed 2℃, the salinity should not exceed 5‰, and the PH should not exceed 0.3, otherwise the survival rate will be easily reduced. If the source water body is different from the water body of the crab apartment, you must cross the water to let the crab have an adaptation process. If there is a big difference, it can be divided into several steps, each time the water passing time is not less than 2 hours, and oxygen is kept during the period, and the dissolved oxygen is more than 5ppm.

Before entering the crab apartment, there is another step to be done, that is, soak the crabs in 5- 10ppm potassium permanganate solution for 0/0 minute to kill parasites and viruses and bacteria on the body surface. The water temperature, salinity and pH are consistent with the water in the crab apartment.

The bait should be fresh or chilled small fish, shrimp and shellfish, and some aquatic plants and other plant bait can be added to the crab. Feed crabs in proportion to their weight. Generally, the daily food intake of small-sized crabs is 8- 12% of body weight, and that of large-sized crabs is 5-8% of body weight. Don't throw too much in a hurry, so as not to waste bait and pollute the water.

The requirements of common crabs for water quality can be adjusted according to the appendix table, so that crabs can live in a suitable environment for feeding and growth.

Second,

Culturing soft-shelled crabs

Crustaceans, such as crabs, undergo molting many times during their growth, and their new shells are soft for a certain period of time. The so-called "

soft crab

"In fact, it refers to crabs that have just shed their shells. Soft-shell crab is a professional soft-shell crab breeding equipment, such as "Crab Apartment", which is used for centralized feeding and fattening of crabs that grow to a certain weight, so that they can be quickly frozen and packaged immediately after molting naturally and become finished products. In this process, there is no need to use any chemicals such as catalysts, which is a healthy and pollution-free organic food.

Soft-shelled crab is a kind of food suitable for all ages. Because all dirty things (including crab's stomach, parotid gland and so on. ) In the process of crab molting, they molt together, which is very clean and hygienic, and 100% is edible. 1. Nutritional value of soft-shelled crab;

1. Soft-shelled crabs are tender and delicious, and can be eaten all over the body;

2. Nutritional components of crab shell: crab roe, crab roe, chitin, chitosan, calcium carbonate and protein. 1) The health functions of chitin are:

(1) Regulate acidic constitution and expel toxins and heavy metals; (2) moistening the intestines to relieve constipation and reducing the absorption of harmful substances in the intestines; ③ Lowering cholesterol and preventing civilized diseases; 4 lose weight and prevent cancer. 2) Health care functions of chitosan: ① antibacterial and immunomodulatory effects; ② the function of lowering cholesterol;

③ Promote cell activation and regulate blood pressure;

④ Prevent and improve diabetes and inhibit fat absorption.

In a word, soft-shelled crab is nutritious and edible all over the body, containing 18 kinds of amino acids. Every 100g contains protein 14.0g, fat 2.5g, carbohydrate 0.8g, zinc 14.2mg, calcium 39.7mg, phosphorus 2mg and iron 37mg except water. In particular, its soft shell is rich in free calcium, which can promote children's growth and development and is a good product for children to improve their intelligence.

In addition, using the "crab apartment" to fatten and shell crabs can greatly increase the added value of crabs, thus increasing the income of aquaculture operators. 2. Water quality management:

Using "crab apartment" to cultivate soft-shelled crabs should be carried out indoors or in greenhouse. In order to ensure the success rate and shorten the fattening time, we should master the water quality conditions and carry out necessary treatment on the water quality.

If the local water source is abundant and the water quality is excellent, the method of "live water culture" or "semi-live water culture" can be adopted according to the specific situation. According to the change of seasonal water temperature, adjust the temperature and disinfect the raw water.

If the industrial recirculating aquaculture (R.A.S) mode is adopted, the water quality treatment mode can be "physical filtration+protein separation (seawater crab)+biological purification+sterilization". The flow of water pump can be selected according to the number of groups of "crab apartment".

Among them, in terms of physical filtration, the "aquaculture microfilter" and "high-speed sand filter cartridge" of China Kehai Company can be selected for water quality treatment. The filtration accuracy of microfilter is usually 75 microns, and the filtration accuracy of high-speed sand filter cartridge can reach about 30 microns. These two devices can be used alone or in combination, and good results have been achieved.

Protein separators can play an unexpected role in mariculture. After physical filtration, some soluble protein dissolved in water is not easy to be removed.

Using protein separator can concentrate black "dirty water" with strong fishy smell in seemingly clear water, thus reducing the content of harmful substances in water and providing better water quality conditions for raising crabs.

Biological purification devices usually appear in the form of "biological water tank" and "biological tower" Because it contains high-density biochemical fillers, it can provide a huge biological attachment area and cultivate a large number of beneficial bacteria, so it can play a good role in treating ammonia nitrogen in water.

In the final sterilization step, you can choose the "ultraviolet sterilizer" of China Kehai Company. The equipment adopts the ultraviolet lamp tube imported from Philips, and cooperates with the high-permeability pure quartz tube, and the killing rate of bacteria and viruses is as high as 99.99%, which fundamentally eliminates the situation that "one person is sick and the whole audience is sick". Let the aquaculture industry truly feel at ease and rest assured. 3. Breeding method (taking Portunus trituberculatus as an example):

50-250g Portunus trituberculatus with incomplete reproductive molting is obtained from natural sea areas or Portunus trituberculatus breeding ponds as molting crabs, and the molting crabs are put into a "crab house" for fattening and breeding, and numbered, which is convenient for management. The specific selection requirements meet the requirements of temporary rearing/fattening, and the higher the fullness, the faster the molting. To prevent sudden changes in temperature, salinity and PH, the water quality should be kept at pH 7.0-8.8, the dissolved oxygen should be above 5mg/L, the salinity should be 24-32, and the temperature should be 18-28℃. Other indicators can refer to the water quality requirements related to fishery culture. Feed crabs at 5- 10% of their weight every evening and/or early morning, and check the molting of crabs every 2-4 hours; After shelling, the soft-shelled crab is taken out and stored in quick freezing or low temperature for sale, and then absorbs water to support the new shell. 4. Feed nutrition and hulling growth:

The feed for feeding crabs should be fresh and low-value aquatic animal feed, which can be chopped and frozen, and fed at 5- 10% of crab weight every evening or early morning, or fed twice a day according to food intake. Regular and quantitative feeding with calcium powder can make crabs shell earlier. In addition, proper shearing is carried out at the tips of crab claws and feet,

It can also effectively promote crabs to shell as soon as possible.

The growth of crabs is accompanied by molting of larvae, molting of young crabs or molting of adult crabs.

Yes, every time a larva molts, it will metamorphose. From the molting of megalopa to the first stage of juvenile crab, its body length and weight will advance by leaps and bounds every time after molting. From each big-eyed larva to the commercial crab over 500g, it takes at least dozens of molts. Every time you molt, you need to absorb a lot of water, so you gain weight obviously when you molt. Related experiments show that the weight of newly molted soft-shelled crabs is increased by 30%-40% compared with that before molting, but in the later growth, water loss is slow and gradually replaced by tissue growth.

The crabs fattened in "Crab Apartment" generally begin to shell in 1- 15 days. As the time for crabs to shell is very short, they should be observed every 2-4 hours. When crabs that are about to shell or are shelling are found, they should be registered and followed up. Once it is found to be a soft-shelled crab, it should be taken out of the "crab apartment" immediately (within two hours), cleaned and classified, and then entered into the next freezing and refrigerating treatment. At this time, the soft-shelled crab is very soft and fragile, has no defense ability against trauma, and will not be pinched by people's hands. We must handle it carefully and protect the integrity of its limbs to improve the appearance of commercial soft-shell crabs.

5. Freezing (fresh-keeping and refrigeration) treatment, packaging and transportation of soft-shell crabs after shelling: the cleaned soft-shell crabs are packaged and shaped, and food-grade plastic bags or plastic wrap can be selected for wrapping, so as to reduce water loss during freezing and improve aesthetics.

In order to keep the soft-shelled crab delicious and delicious, it should be frozen below-18 degrees Celsius during freezing. Frozen commercial soft-shelled crabs can be further packaged and sold in cold storage. 6. Characteristics of high-quality soft-shell crabs:

In order to obtain high-quality soft-shelled crabs, the following characteristics should be met, namely:

1), the crabs before shelling are healthy and pollution-free, and there are no injuries;

2), the body surface is clean, the back is green and the abdomen is white, and there are no parasites and discoloration in the body; 3), natural shelling, appendages intact, no obvious defects and deformities in the body;

4) After hulling, there is no water-absorbing supporting shell, and the fullness is over 9.5%. After thawing, it will not drip when cut; 5), quick freezing in vivo, quick freezing below minus 18-23℃, cold chain in the whole process; 6) The specifications are consistent, and they are packed with nontoxic and environment-friendly packaging materials.

7. Cooking instructions:

? Soft shell crab with salt and pepper

1. Wash the small crabs and cut them into pieces, preferably with the same size. 2. Pour 3 cups of salad oil into the hot pot, and put the small pang when the oil is hot.

Add crabs, fry until crisp, and take out and drain the oil for later use. 3. Leave a little oil in the pot and heat the cardamom powder and coriander.

Stir-fry the powder, then add the crab, material 3 and seasoning, stir well and serve.

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Deodorize the soft-shell crab with whiskey, Chili powder and egg yolk mustard, then wrap it in a thin layer of batter and fry it in a pot. After being baptized by a big fire, the crispy soft-shelled crab has a unique sweet juice flowing out of its mouth. Pepper and salt used to enhance the taste make the overall taste bright. Or, according to everyone's taste, pour boiled cream lemon juice or sweet and sour syrup and hot sauce. ? Fried soft-shelled crab with curry:

Thai flavor offers green, red and Huang San curries to choose from, and green curry is the best. Dip the crab in the egg paste, then dip in the flour mixed with spices such as pepper and pepper, and fry in the oil pan until both sides are yellow. After taking it out, use paper towels to absorb the residual oil, then stir-fry it with high fire, and finally add green curry sauce to serve. This dish is crispy at the entrance, and the rich curry and coconut juice flavors completely penetrate into the crab meat, which is slightly spicy and sweet. The ultra-thin soft-shelled crab, with a gentle bite, tastes crisp and fresh, and also sets off the fragrance of curry.

? Fried crab sandwich

Put the fried soft-shelled crab into a hamburger and sprinkle with tomato sauce or "Tartar sauce" (a sauce made of egg yolk, shredded sauerkraut, olive oil, chives, etc. ), and finally put one or two pieces of lettuce or tomatoes.

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Appendix:

Water quality requirements of common crabs

Conversion table of seawater specific gravity and salinity

The latest fishery water quality standard-fishery water quality standard.

These regulations are formulated in order to implement the Environmental Protection Law of People's Republic of China (PRC), the Water Pollution Prevention Law of People's Republic of China (PRC), the Marine Environmental Protection Law of the People's Republic of China and the Fisheries Law of People's Republic of China (PRC), prevent and control water pollution in fishery waters, and ensure the normal growth and reproduction of fish, shrimp, shellfish and algae and the quality of aquatic products.

1 Subject Content and Scope of Application 2 Reference Standards 3 Fishery Water Quality Requirements 4 Fishery Water Quality Protection 5 Standards Implementation 6 Water Quality Monitoring Supplementary Notes:

Subject content and scope of application

This standard is applicable to spawning grounds, feeding grounds, wintering grounds, migratory passages and aquaculture areas of fish and shrimp and other marine and freshwater fishery waters. 2 reference standard

GB5750 Standard Test Method for Drinking Water

GB6920 Water quality-Determination of PH value-Glass electrode method

Determination of hexavalent chromium in GB7467 water: Determination of total mercury in water by GB7468 dicarbonyl hydrazide spectrophotometry: Cold atomic absorption spectrophotometry.

GB7469 determination of total mercury in water quality-dithizone spectrophotometric method with potassium permanganate-potassium persulfate digestion method

GB7470 water quality-determination of lead-dithizone spectrophotometric method

Determination of cadmium in GB747 1 water: Determination of zinc in water by dithizone spectrophotometry GB7472: Dithizone spectrophotometry.

GB7474 determination of copper in water quality GB7475 determination of copper, zinc, lead and cadmium in water quality GB7479 determination of ammonium in water quality GB748 1 determination of ammonia in water quality GB7482 determination of water quality * by ion-selective electrode method.

GB7485 Determination of Total Arsenic in Water Quality GB7486 Silver Diethyldithiocarbamate Spectrophotometric Determination of Cyanide in Water Quality Part I: Determination of Total Cyanide GB7488 Five-day BOD5 Dilution Inoculation Method GB7489 Determination of Dissolved Oxygen in Water Quality Iodometric Method.

GB7490 determination of volatile phenol in water after distillation 4- aminoantipyrine spectrophotometry GB7492 determination of bhc and DDT in water quality gas chromatography GB8972 determination of sodium pentachlorophenol in water quality gas chromatography GB9803 determination of chlorophenol-free in water quality saffron t spectrophotometry GB11determination of kjeldahl nitrogen in water quality.

GB 1 190 1 determination of suspended solids in water quality gravimetric method

GB 1 19 10 water quality-determination of nickel-butyl copper oxime spectrophotometric method

Gb11911determination of iron and manganese in water; Determination of nickel in water by flame atomic absorption spectrophotometry GB 1 19 12: Flame atomic absorption spectrophotometry.

3 fishery water quality requirements

3. 1 The water quality of fishery waters shall meet the fishery water quality standards (see table 1). 3.2 The standard value refers to the maximum allowable value of a single determination.

3.3 If the standard value exceeds the standard value, it means that the normal growth and reproduction of fish, shrimp and shellfish cannot be guaranteed, and the harm degree should be comprehensively evaluated with reference to the background value, fishery environmental survey data and relevant fishery water quality benchmark data.

Table 1 Fishery Water Quality Standard

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4 Fishery water quality protection

4. 1 All enterprises, institutions and individual operators must take effective measures to ensure that the water quality of fishery waters meets this standard in the near future.

4.2 Untreated industrial wastewater, domestic sewage and hazardous waste are strictly prohibited to be directly discharged into fish and shrimp spawning grounds, feeding grounds, wintering grounds, fish, shrimp, shellfish and algae fields and precious aquatic animal protection areas. 4.3 It is strictly forbidden to discharge sewage containing pathogens into fishery waters; If such sewage needs to be discharged, it must be treated and strictly disinfected. 5 standard implementation

5. 1 The implementation of this standard is supervised by fishery superintendency agencies at all levels, and the implementation is regularly reported to the environmental protection department of the people's government at the same level.

5.2 If the local fishery water quality requirements cannot be met during the implementation of the relevant national pollutant discharge standards, the people's governments of provinces, autonomous regions and municipalities directly under the Central Government may formulate local pollutant discharge standards stricter than the relevant national pollutant discharge standards to ensure the fishery water quality requirements, and report them to the environmental protection department and the fishery administrative department of the State Council for the record.

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5.3 If the items exceeding this standard cause obvious harm to the fishery, the provincial fishery administrative department shall organize relevant units to formulate local supplementary fishery water quality standards, which shall be submitted to the provincial people's government for approval and reported to the environmental protection department of the State Council and the fishery administrative department for the record.

5.4 The mixed zone formed in the waters where the sewage outlet is located shall not affect the fish migration channel. 6 water quality monitoring

6. 1 The monitoring requirements of various items in this standard shall be monitored by the specified analytical methods (see Table 2).

6 .2 Water quality monitoring in fishery waters shall be conducted by fishery environmental monitoring stations organized by fishery supervision and management institutions at all levels.

.

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Note: The following methods are adopted for the time being, which will be implemented after the release of national standards. Water quality inspection Method of Fisheries was promulgated by the Ministry of Agriculture, Animal Husbandry and Fisheries on 1983.

The measured result is the total ammonia concentration, which is converted into nonionic ammonia concentration according to Table A 1 and Table A2. The Method of Monitoring and Testing Surface Water Quality was promulgated by the Institute of Health of China Academy of Medical Sciences on 1978. Appendix A Total Ammonia Conversion Table (Supplementary) Appendix A Total Ammonia Conversion Table (Supplementary) Table A 1 Percentage of nonionic ammonia in ammonia solution

Table A2 Total ammonia (NH +NH3) concentration, in which the nonionic ammonia concentration (NH3) is 0.020 mg/l (mg/L).

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Additional notes:

This standard is proposed by the Standards Department of the State Environmental Protection Agency. This standard was drafted by the revision group of fishery water quality standards.

This standard entrusts the Fishery Administration and Fishing Port Supervision Administration of the Ministry of Agriculture to be responsible for the interpretation.

(1989 August 12 Approved by the State Environmental Protection Bureau and implemented in March 1990)

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