First, the basic knowledge of crabs crab, people generally call it hairy crab, because the chewing foot has a lot of fluff, usually called crabs, named after its rampage, it is also known as rampant generals. As the proliferation of lakes and large water surface is also called water hairy crabs, Yangtze River basin called Yangtze crab, Liaohe river system called Liao crab. Scientific name mitten crab.
Crabs like to play in the caves, often hidden in the stone crevices, water plants, underwater, daytime in the cave or in the grass, out at night for food. Faster growth, the general life of 2-3 years, the longest individual can live for four years, the requirements for the water body to be slightly alkaline, PH value of 7.5-8.5, suitable for the growth of water temperature around 18-30 degrees Celsius, the best growing water temperature 22-28 degrees Celsius. Dissolved oxygen in water requires more than 5 mg/l, with clear flowing water being the best. Crab and fish are hypothermic animals, and body temperature rises and falls as the water temperature rises and falls. It has a wide diet, is omnivorous, animal-oriented, likes to eat dead fish and rotten shrimp and dead animal carcasses, organic debris, small snails, insects and larvae, etc. Under normal circumstances, crabs predatory food bait It's easier than animal food. In natural life, the proportion of food is mainly plant-based diets, mostly plant debris on the shore, filamentous algae, willow leaves, black leaf algae, duckweed, etc., and can also eat artificially-fed vegetables. Young grass, potato silk, grain, cereals, bran bran and so on. Artificial feed, animal internal organs, etc. also love to eat. Crab's digestive ability is very strong, bulimia, eating a large amount, the food produced after eating satiety will be stored in the liver. The ability of the crabs to starve and hungry is also strong. In the absence of food, ten days and a half months without food will not starve to death. The temperature has a direct impact on the feeding of crabs. When the water temperature is above 15 degrees Celsius, the food in the stomach is full. When the water temperature is around 10 degrees Celsius, the food in the stomach is half full. When the water temperature is below 10 degrees Celsius, the metabolic function is weak and it is rarely eaten. Do not eat in the pit during the winter.
Crab is a genital migratory animal. It grows in fresh water throughout its life. When it is sexually mature, it begins to descend to the river for a lifetime of reproductive migration, and it is bred and bred in shallow seawater in the estuarine area. Crabs are fighting for food with aggressive nature, often fighting for food and fighting with each other. They also kill each other when the density of bait is low. Injuries, incomplete limbs, and just-shelled â€œsoft-shelled crabsâ€ tend to By the same kind of attacks and encroachment, this must be paid attention to by artificial crabs.
Crab is a crustacean, and the shell is an important symbol for the growth and development of crabs. Because the crab's limbs are all covered with carapace, only the larvae's cicadas and young clams can change the shape and shape of the crabs. Increase. In growth and development, once each clam shell, body shape will increase once and complete limb regeneration through the oyster shell. The life of crabs is about 20 times in their life. The growth and development time of each crab is not the same as the length of life. The size of the individual who grows up to sexual maturity and the number of shells are different. Some individuals are very large, others are Very small. It has been observed that two days before the crabs approached the oyster shell, they moved slowly and did not eat. They climbed into the water grass and attached their limbs to the plants. The crab shell first cracked from the junction between the back edge of the head breastplate and the abdomen, and cracks were also formed at the junction between the side line plates on both sides of the mouth. Then the head breastplate gradually rose upwards, the cracks expanded, and the crab body shrank abdomenly. On both sides of the body, the body oscillates and contracts to the middle and back. The first step is taken out, then the abdomen is withdrawn. Finally, the chewing foot is withdrawn to complete a growth process. After the oyster shell, the original new body wrinkled, gradually stretched, absorbing water, the body shape increased a lot, slowly climbed into the water grass crouching quietly, two days later, the soft new shell gradually hardened, then Start foraging activities.
Each time the crab shells are reborn, it is a once-in-a-lifetime experience. The shell can be completed within 15-30 minutes, and sometimes even 3-5 minutes can complete the whole process of the shell. However, in case of disturbance, drought or malnutrition, the shell time will be prolonged. Sometimes one or two feet can't get out of it and stay in the old shell. At this time, the soft shell crab lacks the one or two footsteps. Sometimes the entire body can't die from the old shell and die, saying that the shell had not died. Crabs or freshly-cracked soft-shelled crabs that are in the process of shelling often encounter hostile attacks, and soft-shelled crabs are also eaten by similar species. Therefore, in the process of raising crabs, the most fundamental thing is to strengthen the feeding and management, improve the environment of the shell, promote the smooth shelling of the crab to increase the survival rate, and increase the rate of return.
In order to obtain good benefits, artificial crabs must be combined with the actual situation. Here are some of the most basic questions and points about raising crabs.
Second, the water area is the condition of artificial crabs to choose what kind of water is very important, the water area is the basic conditions for artificial breeding, proliferation of crabs, there is no good water without good benefits. There are many types of waters, including ponds, rivers, reservoirs, and lakes. The types of aquaculture include large water surface containment, large water surface proliferation and release, cage culture, and small water surface intensive cultivation, as well as paddy fields, reeds, and shallow-swept cultures. Various types of waters have different requirements for the stocking of juvenile crabs. The rate of recovery of the crabs in different water areas, the size of the multiplication ratio of the population, and the input-output ratio are all different. At the same time, the individual size of adult crab, fullness, economic benefits, and color of carapace are all significantly different.
The conditions of the water area include the location, direction of the water, the temperature of the water, the source of the water, the quality of the water, the adequacy of the light, the depth of the water level, the amount of grass, and the abundance of the natural food. These are related to the water area and the suitable water environment. It is a prerequisite for the survival and growth of crabs. Therefore, the selection of water conditions is one of the aspects that people cannot ignore.
In the waters of cultivated crabs, aquatic weeds play an important role in the growth and life of crabs. There are a certain amount of aquatic weeds in crab ponds, which is conducive to foraging, inhabiting, hiding, and growing pods of crabs. A suitable ecological environment will help river crabs escape the invasion of predators. Aquatic plants can also purify and improve water quality. They can absorb ammonia, nitrogen, and inorganic nutrients in water and reduce the fatness of desalinated water. At the same time, the use of photosynthesis to produce and increase dissolved oxygen in water can help meet the needs of river crabs for dissolved oxygen. At the same time, aquatic plants can also increase the transparency of the water body and have a certain stabilizing effect on the pH of the water body.
Grass-type lakes and reservoirs have the best effect on proliferation and release. General stocking specifications are about 80-100 kg/kg, and the rate of catch-return is up to 60%. Individual crabs can reach 125 grams or so, and the population multiplication factor can be up to 15 times. Lakes and lakes rich in bait are generally not required to feed bait, but the density should not be too large, and no more than 200 waters per acre. To strengthen daily management, it is forbidden to use fishing rods and grasses in the breeding lake to avoid harming young crabs, especially shell crabs. To prevent crabs from escaping from the water inlet and outlet, pay more attention during the flood period. Don't castor in the lake where crabs are raised, because river crabs are extremely sensitive to the leach of hemp and can easily cause death.
Third, seed quality is the key seed quality, the type of juvenile crabs and dry storage time, storage in long-distance transportation is the key to the survival rate of juvenile crabs. They are indispensable. There are both seedling problems and technologies. Inadvertently lead to death. What kind of crab is best? We all know that it is well-known that the Yangtze River Crab is well-grown, and that the gonads of the Yangtze River crabs have matured late and are long. When buying crab species, we must pay attention to it. We can't figure out whether it is cheap or not. If you want to buy crabs, be sure to distinguish the crabs from the cage crabs, old crabs, crabs, and crab traders. These crabs are cheap, but they have no benefit after stocking.
To purchase crab species, we must choose a healthy body, a strong physique, and a disease-free, non-injury stocking. The density depends on the crab species specifications and feeding conditions. It is better to put 500-1000 acres of oysters in the pond. It is better to put early investment in the year, preferably in March-April with ice, to adapt to the environment and facilitate transportation.
Before releasing the crabs, please note that if the purchased crabs are transported for a long time, they should be soaked in water for 2-3 minutes, removed after 10 minutes, and then put in water for 2-3 minutes, and then take out the flat, so repeatedly 2 times, then put in the culture pond.
Fourth, anti-escaping is fundamentally like climbing crabs is the nature of the crabs, crabs must prevent fleeing, no escape without benefit. It is very important to prevent the escape of crab ponds. As the saying goes: "Fighting crabs is not good at preventing fleeing. Kung fu is running away. It's not good to prevent fleeing from pests. It's not effective to spend money." There are many ways to artificially escape crabs. It's usually practical now. The plastic film was prevented from escaping. A closed protective wall was enclosed around the pond with a special thick plastic film. The plastic was 60 cm above the ground and 15 cm underground. It was firmly attached to the bamboo raft that was inserted into the ground. This method is simple, investment is not large, the effect of anti-escape is better. Within 100 mu of water area and the relatively scarce waters of bait organisms must be built anti-escape facilities before meeting the requirements for crabs. Large-scale aquatic plants and large reservoirs of lakes generally do not need to prevent escape. However, at the inlet and outlet of the fish, fish nets and bar grills are built to prevent fish from escaping and escape crabs. To start catching ahead of time, the fishing date must not be too late. Before escaping from the genital migration, before and after Chongyang and in late September, timely capture should be made to artificially control the number of crabs to escape.
Fifth, management is to ensure that management plays an important role in artificial crab cultivation. If management is not done well, the benefits will not come. There are many contents of management, such as casting, water quality and water level adjustment, temperature control, disease prevention and escape, and how to prevent harvesting. Do it in a Tube , hold it in the end and hold it tightly. Crabs in ponds need to be â€œtimed, positioned, qualitative, and quantitativeâ€ and should be fresh and palatable, not too little or too much. Too little to eat, excessive contamination of water, causing waste. In the early stage, the cast was mainly green, coarse, and refined. Green material (water grass and the like) accounted for 30%, coarse material (branch grain) accounted for 40%, and fine material (mixed fish and animal waste) accounted for 30%. Promote crab volume growth. In the later stage, the cast is mainly fine, coarse, and blue, which means that concentrates account for 60%, coarse and green are about 20%, and the liver accumulation of crabs is promoted, and the body weight is increased.
Water quality citations should be hygienic, non-pollution, adequate water supply, fresh water, adequate dissolved oxygen, and a transparency requirement of more than 30 cm. Maintaining a suitable water level, ponds should constantly raise fresh water to meet the requirements of river crabs for water activities and promote growth. .
The crab disease is not much, the most important is the clam shell disease. Crab ponds should pay attention to the fresh taste of dipping material to ensure the nutritional quality of dipping material. Regularly improve water quality, increase calcium fertilizer, and increase calcium ion content in water. In the summer and fall season, lime is used once every 20 days, and about 15 kilograms of mu are used. After melting, it spills into Quanchipu.
Conscientiously do a good job of preventing escape, prevent damage, and prevent theft. Usually, we must strengthen supervision and check the maintenance and escape prevention facilities from time to time. Regardless of the type of material used to prevent escape, it is important to ensure that the crabs do not escape. On the basis of doing a good job of preventing flight, we must further strengthen the prevention of damage, and we must try to eliminate flooding and dry mice, drive waterbirds, and weasels. Drought and water mice were killed by drugs and they were advised to take drugs far away from the water in order to prevent crabs from eating and causing death.
Crab fishing methods are varied, including the dry pond method (for pond breeding), crab and earthworm (large water surface catch). Regardless of the method used, it is necessary to seize the season and lose no time to harvest all the crabs and increase their profits.
In order to concentrate on sales, it is necessary to raise them. The pond selection for raising crabs is the same as the normal artificial crab ponds. First of all, we must build anti-escape walls, use nets at the inlet and outlet, block the loopholes, prevent escape from crabs, and try to simulate the natural ecological environment. Add new water, maintain water quality, feed animal feed, promote crab body weight gain, and prevent disease and damage. Spotted market conditions and timely sales.
The above points are the basic points of river crab breeding, and they are also the main essences. To sum up, there are four sentences: â€œThe water area is the condition, the seed is the key, the anti-escape is the fundamental, and the management is the guarantee.â€ As long as these words are closely To do it will generally achieve very good results.
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