What should be done in the ecological breeding of pond crabs?

Clear pond disinfection: first check whether the bottom mud of the pond is about 15 cm, the bottom mud is too thick to be removed, only 15 cm of bottom mud is retained, and then a certain period of exposure is carried out, 7 10 days before the seedlings are put into each mu with 100 150 kg of quicklime to thoroughly clean the pond and disinfect, 7 10 days after putting in 50 70 cm of new water. If it is a pond with water, the amount of quicklime per mu is 150 300 kg.

2. Construction of anti-escape facilities: The construction of anti-escape facilities should be done while the pond is disinfected. The anti-escape facility can be buried in the soil with 80 cm of asbestos tile inclined inward at an angle of 15 degrees, and enclose the pond around, and no gap can be left between the asbestos tiles to prevent escape crabs.

In addition, dense mesh cloth, bamboo poles and hard plastic sheets can also be used to build anti-escape facilities. The method is to dig a small trench 15 cm deep around the pond, bury it in a dense mesh cloth, and then bury a bamboo pole every 5-10 meters along the dense mesh cloth, and tie the mesh cloth to the bamboo pole to fix it, and finally sew a hard plastic cloth on the upper part of the mesh cloth.

Farmers have a saying that "the size of the crab depends on the aquatic weeds", which shows that the cultivation and maintenance of aquatic weeds is one of the key technologies of river crab farming. Crab pond commonly used aquatic weed species are elophylla, black algae, bitter grass, weed, etc., aquatic weeds are planted 15 days after disinfection in the pond, generally from January to early February, about 20 cm of water. The pond is planted in the shape of "well", the spacing of the aquatic weeds is meters, the spacing between the plants is meters, each grass belt is 4 5 rows of aquatic weeds, the width is meters, and the blank area of 2 3 meters is left between the aquatic grass belts, leaving space and routes for river crab activities, and at the same time can also ensure the smooth flow of water.

Elophyllum should be planted as early as possible, generally in early January, and planted in the temporary breeding area of river crabs; Late planting of leaf black algae, bitter grass and other late aquatic weeds, late aquatic plants are planted around the end of February, planted in the conservation area, and need to be separated by mesh to protect the germination of aquatic plants and prevent them from being destroyed by river crabs.

Ecological Aquaculture Technology of River Crab Pond Abstract This paper summarizes the ecological breeding technology of river crab pond from the aspects of crab seedling selection, water quality control, cultivation of aquatic weeds, pest control, scientific baiting, daily management, and timely capture and marketing. Keywords: river crab; pond culture; CLC Number Literature Identification Code B 1 Selection of crab seedlings Crab seedlings with bright body color, no disability and no disease, strong activity and no secondary sexual characteristics should be selected to ensure that the yield of adult crabs is more than 2 250 kg hm2. 2 Water quality control Crab farming has high requirements for the quality of the water environment, and the water quality must be scientifically regulated.

The water quality of the crab pond generally requires a transparency of 35 40 cm, dissolved oxygen of more than 5 mg l, pH value, and ammonia nitrogen concentration mg l. The above water quality indicators can be tested by means such as water quality test boxes. If there is more silt at the bottom of the pond, the transparency is low, the water color becomes thicker, the back of the river crab is dark black, the abdomen appears rusty, and the end of the foot turns yellow, so take measures to improve and improve the bottom environmental conditions, keep the bottom clean, the water quality fresh and the dissolved oxygen sufficient, so as to meet the needs of its growth.

After high temperature, especially more rain, and the weather temperature changes greatly, it is easy to cause hypoxia in the water body, aquatic weeds sink, rot and die, deteriorate the substrate, cause water quality to deteriorate, cause ecological environment damage, affect the later growth of river crabs. To this end, the following measures should be actively taken; Regular injection of new water is generally 7 10 days 1 time, and the amount of water exchange is about 20 of the water body. The water level is generally controlled at 1 m according to the principle of "shallow in front, deep in the middle, and moderate in the back"; Avoid pesticides during the use period when changing the water, and inject water on the day or day before the application.

At the same time, quicklime slurry is often used to splash the whole pool, and it is used continuously for 2 3 times, with an interval of 5 7 days each time, which can adjust the water quality, which is conducive to the growth of river crabs and the change of crab shell color. Use substrate improvers and water quality regulators to regulate water quality, and use photosynthetic bacteria, bacillus and other microorganisms to absorb toxic substances in the water and at the bottom of the water (such as hydrogen sulfide, ammonium salt, etc.); The use of bottom improvers such as bottom Jule to improve the bottom of the pond sludge, decompose the harmful substances such as hydrogen sulfide and ammonia nitrogen in the bottom sludge of the pond, so as to improve dissolved oxygen, stabilize the pH value, improve the immunity of the river crab, can significantly improve the yield and quality of the river crab, and the water quality and ecological environment should be used once in 10 15 days. Replenish and manage aquatic plants (such as elophylla, bitter grass, water peanuts, etc.) in the crab pond.

Water body aeration should increase water convection after hot weather, foggy weather and rain, increase oxygen to ensure the demand of river crabs for dissolved oxygen, and prevent water hypoxia from causing stunted growth of river crabs. 3 Cultivating aquatic plants and aquatic weeds not only provides natural bait for river crabs, but also regulates the water temperature and provides a hiding place for river crabs.

1. Pond disinfection: When breeding crabs in the pond, it is necessary to remove excessive silt at the bottom of the pond, and sprinkle quicklime for disinfection and sterilization after drying for 20 days. 2. Crab seed stocking:

Select undamaged crab species and put them in the pond in February and March every year, and the density is maintained at about 550 crabs per mu. 3. Feed feeding: provide feed for crabs twice a day, and animal feed is the main one in the early stage.

1. Cleaning pond disinfection

Before breeding crabs in the pond, the water in the pond should be drained, and then the excessive silt at the bottom of the pond should be removed, and the thickness of the silt should be controlled at about 10 cm, and then dried for 20 days, and then injected with water, and 400 kg of quicklime per mu should be sprinkled to disinfect and sterilize and improve the quality of the silt.

2. Crab seed stocking:

When breeding crabs in ponds, it is necessary to select crab species with neat specifications, no damage, and sound limbs for stocking, and the stocking density is 500-600 per mu, and the stocking time can be selected between February and March each year, so as not to stocking too early, resulting in frostbite and death of crab species.

3. Feed feeding

In the process of breeding crabs, feed should be fed twice a day, once in the morning and once in the evening, and after each feeding 1-2 hours, the food residues should be cleaned up, and in the early stage of breeding, fresh fish and shrimp and other animal bait should be provided for the crabs, and plant feed can be increased in the later stage of breeding.

1 Selection of breeding sites:To choose the breeding site of the blue crab, it is necessary to create a warm habitat in winter and cool in summer and a superior ecological environment for growth and development according to the requirements of the ecological habits of the blue crab. At the same time, it should also have the conditions to facilitate production and operation.

Specifically, the farms of blue crabs should choose an inner bay with less wind and waves, with good seawater exchange, smooth tidal flow, appropriate proportion of seawater, not affected by industrial and agricultural pollution, and the main water quality indicators meet the fishery water quality standards. At the same time, the fresh water source is sufficient, the transportation is convenient, the crab seedlings are convenient, and the site with sufficient fresh bait can be used for the breeding of blue crabs. But there are a few things to keep in mind:

Choose calm winds, smooth currents, and flat terrain. There are conditions for desalination and flood drainage, convenient construction, and small amount of work on both sides of the inner bay shoal or harbor road. The elevation of the bottom of the pond is equivalent to the tide level in the mid-tidal zone, and the water depth can be maintained above the meter after the tide.

The bottom quality is better to be sediment, if there is a lot of mud at the bottom of the pool, coarse sand or broken shells should be added to improve the soil. The specific gravity of seawater is always maintained and is not affected by infiltration water from the terrestrial ground. There are no pesticide factories or chemical plants nearby, and they are not affected by the situation of industrial sewage.

Low-value fish, shrimp, shellfish**abundant, convenient transportation, electricity**.

2 Crab pond areaIf the area is too large, it is difficult to drain and irrigate, and it requires a lot of manpower and material resources. At present, the seedlings mainly come from natural fishing, the quantity is limited, the specifications and quality are different, and the time of cultivation is also inconsistent, so it is necessary to feed in different ponds according to different specifications, the area is too large, and the seedlings are insufficient, which wastes the water surface and is difficult to harvest.

At present, many areas use idle shrimp breeding ponds to breed saw-edge blue crabs, with an area of 20 30 acres.

3 Crab Pond Construction:It can be divided into single pond, double pond and Tianzi-shaped pond. A pond and a gate are called single ponds, two ponds are close to three gates, and one of the gates communicates with two ponds called double ponds.

The four ponds are connected into a field zigzag called a Tian zigzag pond. Specifically, a saw-edge blue crab pond is generally composed of embankments, sluices, beaches, ditches, escape prevention and anti-fighting facilities.

The ditch is the main ditch of the pool, and when the inlet and drainage sluice is separated, the ditch is connected by the inlet sluice and the drainage sluice, and communicates with the ring ditch and the branch ditch. **The depth of the ditch is generally more than meters. The ring ditch is a ditch excavated along the pond embankment, in order to protect the embankment, there should be a certain distance between the ditch and the embankment foundation, generally 3 6 meters.

The annular groove can sometimes be used in place of the main groove. The branch ditch is the water ditch that connects the ** ditch and the ring ditch, and its width is half of the ** ditch. Generally, there are no branch ditches in crab ponds.

Only ponds with a large area have branch ditches.

It is necessary to determine according to the specific situation, try to choose a place with living water, so that we can better carry out aquaculture, and correct the depth of the pond and the size of the pond.

It is best to choose the inner bay with less wind and waves, the quality of the water is better, and the circulation is better, so that the breeding can be better.

Attention should be paid to the following points in fish pond and crab farming:

1. Pay attention to the depth of the silt.

The silt in the original fish ponds is relatively deep and fertile. The silt that is too deep and too fertile is not good for fish farming, and it is harmful to crab farming without any benefit, so it must be dredging and transforming, leaving only about 10 cm to plant aquatic weeds, so as to ensure that the disease is removed, the water quality is fresh, and the aquatic weeds can grow luxuriantly. The removed silt should not be left on the inner slope of the pond like fish farming, but should be completely transported out of the pond to prevent rainwater from rushing back into the pond, overpowering the escape wall and causing the pond water to become turbid.

Second, pay attention to the number of aquatic plants.

Most of the ponds where fish have been raised for many years have little or no aquatic weeds, which is very unfavorable for crab farming. As an extremely important environmental factor for the growth of river crabs, aquatic weeds provide a necessary place for river crabs to perch, forage, avoid enemies, hide and molt, and can also purify water quality and provide other vitamins, crude fiber and other substances lacking in bait. Therefore, the original fish pond should be converted to crab breeding in a timely manner, many times, in an appropriate amount (the aquatic grass area accounts for about 60% of the pond area), sparse and mixed transplantation of multiple groups and varieties, such as:

Aquatic plants such as black algae, elos, bitter grass, and sorrel are very important.

3. Pay attention to water seepage in the pond.

Water seepage that is not harmful to fish farming, whether it is internal or external infiltration, must be paid great attention to. Because for crab farming, water seepage is not only a problem such as losing pool water or adding "good water", but also the escape of river crabs along the "waterway", and even causing problems such as empty ponds and "black pools" without crabs. Therefore, the original fish pond is converted to crab farming, and it is necessary to pay close attention to it in the pond cleaning and patrolling the pond at ordinary times, and find that the seepage that causes the river crab to escape should be tamped and blocked in a timely and effective manner.

Fourth, pay attention to the environment.

River crabs are timid by nature, and their external sounds change strongly, such as when people and animals approach, it will affect their normal habitat and foraging. Especially in the process of molting the river crab, if it encounters external interference, the molting time will be prolonged, which will affect the physique after molting, and the heavy one will not be molted, which will cause death at that time. Therefore, keeping the crab pond quiet is an issue that must be paid great attention to, and the noisy environment of the original fish farming environment must be rectified.

Fifth, pay attention to the enemy.

Mice, crayfish and other predators that are not much harmful to the original fish farming exist more or less in fish farming ponds, and fish farmers do not pay much attention to them. But for crab farming, mice, crayfish and other enemies are very terrible: a mouse can bite to death and eat at least 8 juvenile crabs of about 5 grams a day; A crayfish can attack 2 or 3 freshly molted soft-shell crabs in an hour.

Therefore, when the original fish pond is converted to crab breeding, it is necessary to thoroughly clean the pond before stocking, improve and strengthen the anti-escape board and drive away and kill rats, crayfish, birds, yellow eels, loaches, etc. at any time to ensure a good crab breeding environment.

Sixth, pay attention to Qingtang.

Although quicklime can provide the calcium required for river crab molting, but because the pH of the pond water is relatively high, if the pond is cleared with quicklime, it is bound to increase the pH value of the pond water again, which is not conducive to the molting and feeding of young crabs. Therefore, the fish pond cleaned with quicklime must be changed to the crab pond with bleaching powder.

1.Water quality;

2.dissolved oxygen; 3.Fodder;

4.Plants; 5.whether the living space of fish and crab overlaps; whether the eating habits are the same or similar; whether they kill each other;

6.Whether there is a conflict in the time to market.

How to change the fish pond to the crab pond and the pond is too fat.

1. Choose a pond: The soil in the pond should be clay, sand or sub-sandy soil, and the water quality should be clean. 2. Clean the pond:

Before raising crabs, the pond is disinfected with bleaching powder. 3. Reasonable seedling: soak the crab seedlings in water for 5-10 minutes before putting them into the pond.

4. Daily management: feed the crabs once a day in the morning and once in the evening.

1. Select a pond

Crabs are reared in freshwater in ponds, using clean water quality, and with adequate water** and ventilation, the soil in the pond is preferably clay, sandy or sub-sandy, and the water depth is kept between meters.

2. Clean the pond:

In the case of newly built freshwater aquaculture ponds, crabs must be sterilized with bleaching powder before they are stocked, and about 150kg of organic humus fertilizer must be placed in the pond 3-4 days after disinfection.

3. Reasonable seedling

Choose high-quality crabs with neat specifications, complete steps, strong physique, and active crawling, soak them in water for 5-10 minutes, and wait for the young crabs to absorb enough water and adapt to the water temperature, and then put them in the pond, which can improve the survival rate.

4. Daily management

In the process of freshwater aquaculture of crabs, it is necessary to feed once a day in the morning and evening, and the principle of fine, green and coarse reasonable collocation should be adhered to when feeding, and the feed is mainly trash fish, snails, fishmeal, aquatic weeds and potatoes.