How to breed crabs

Step 1 | Select the entrance of the hall

Choose a site suitable for raising crabs;

Paddy field is the best, followed by dry land in lake beach and reed beach.

The soil bone should be yellow bone and streaky soil, preferably. Black clay comes second, blackboard sand comes last.

The soil with pH value of 6.5-7.8 is the best, followed by 6-7.5, and 7.5-8.5 is the worst.

Water source:

Mainly close to natural water sources, it is best not to have factories in big lakes, rivers and upstream. There is no sewage from people and factories along the15km water source, so chemical enterprises are the most taboo water source.

Open the pond:

The ratio of embankment slope around the dam is 3: 1, and the height of the dam is 1.2 m, which is mainly used for raising large crabs, and there are gentle slope ditches with a width of 50 cm and 3 m around it. More than 50 acres, with a cross ditch in the middle.

The water inlet and the water outlet are fixed.

Anti-escape fence design:

Mainly pvc board, about 55Cm-75Cm, half buried in earth dam. Bamboo poles are erected at the interval of 1m5, and the height is about 1m8. Buried 30cm under the soil, wrapped with 5 mesh barbed wire or nylon net to prevent theft.

Construction of nursing room:

We should ensure that there is a feed warehouse, a feed cooler and a fishing gear room for storing other tools. If possible, we should build a living room, water and electricity lines and testing equipment.

The first reform after opening the pond;

Open the Tangkou well, put an 80cm bubble pool first, check the leakage point, repair it, and measure the water quality one week later. According to the water quality report, calculate the reduction of lime and other materials, and use water to change the bottom of the pool.

After the first bottom modification, return to the water again, measure the water quality one week later, and after reaching the standard of nutritious water, kill and disinfect with bleaching powder or chlorine dioxide.

Drain water after three days, topdressing organic fertilizer, and burying 200-300 kg of self-made organic rot fertilizer per mu. Then plant Elodea in the ditch and return the water after planting. 35-50 cm (Sakata)

| Step 2 | Planting grass

After loading Elodea in the ring ditch (after 300 kg of fresh grass per mu), the backwater began to drain. After three days, the first fertilization was carried out, and the long-acting organic fertilizer and various bacterial sources were cultured simultaneously. When necessary, add inorganic fertilizer to assist, and after obtaining satisfactory water phase and algae phase, keep the water body about 50Cm in the board yard and start preparing for the first winter snail pond work.

The quality control of screws and the water quality requirements of soup mouth have been written separately, so I won't repeat them. Let's talk about the number of screws this time. Each acre needs 60-80 screws, 500-800 kg, and the screws should be put into the pond at one time. Put the screws in the ditch by manpower and boat, and be careful not to pile them up, not to put them in when the temperature is low, and not to throw them in the snow and ice weather.

3 days-1 week after the screw is put in, the water quality and algae intersection in the pond should be observed in time. Found that the water quality is too clear and thin. After the fungus is fermented, it is baked twice with soybean milk and Tang Hongshui, 5 kg per mu, with an interval of 2-3 days.

During this period, whether the pH value and dissolved oxygen are abnormal should be measured once.

Half a month after feeding snails (after New Year's Day 10 days, choose sunny days), put shrimp fry for the first time, and the weight is about 5 kg.

And start feeding rapeseed meal+soybean meal every 3-4 days, about 1 kg per mu, and stop feeding when the weather reaches freezing point.

Auxiliary fish: it is necessary to release a certain amount of various fish at the mouth of the pond to balance the water quality. Because the eggs of all kinds of miscellaneous fish contained in natural water will enter the pond mouth with the water source, it is an effective means to control miscellaneous fish with mandarin fish to prevent the subsequent feed from being consumed. It is suggested to use about 5-18 fish per mu, depending on the amount of miscellaneous fish in the water body. In addition, put 3 silver carp (1 white 12 yellow) per mu, and 2 juvenile fish per catty. And put the local crucian carp in about a catty, about two catties, and half a catty of crucian carp belt, one per mu. 2-3 grass carp can be put in a 30-mu pond.

| Step 3 | Crab in seedling

Generally, Xintangkou adopts the binary method of winter seedlings and spring seedlings, and the old Tangkou adopts the method of transplanting seedlings and spring seedlings. Winter seedlings are generally less than 80, and the seedlings with uniform individuals are better. Spring seedlings are generally less than 60, and even seedlings are better. If the goal is to raise crabs, the specifications of spring seedlings should be well controlled: mainly seedlings with less than 40 heads). There are about 400-500 winter seedlings and 800- 1000 spring seedlings.

In mid-July, the old pond was released, and soybean seedlings (250 ~ 300 per catty) were about 1.5 kg per mu, and starved from October to February, so that the phenomenon of old seedlings was kept within 10%, and the individual weight could not exceed. Reasonable control of nutrient intake is the key.

Spring seedlings, 60 large seedlings with 800 heads per mu, went to the pond about 15 days before Qingming.

Note: Because the spring seedlings go into the pond, it is found that the seedlings have a top shell and sticky fertilizer when they molt for the first time, so they must be replenished. Moreover, vitamin E should be added to the feed for adjustment.

| The fourth step | Planting grass

The size of crabs depends on aquatic plants, which largely determine the specifications and yield of river crabs. Aquatic plants play an important role in raising crabs in ponds and are indispensable technical measures for raising crabs. The planting area of aquatic plants accounts for more than 50% of the pond area. Several kinds of grass should be mixed to prevent too many aquatic plants and pests, and they should be cut off. Too few aquatic plants should be transplanted in high temperature season, and rotten aquatic plants should be removed in time.

Control the coverage of aquatic plants according to different growth periods. 20-30% in spring, 55% in summer and 30-40% in autumn. When there are too few aquatic plants, replanting or transplantation should be carried out appropriately. When there are too many aquatic plants, technical measures such as stubble cleaning, slowly deepening the pool water and increasing dissolved oxygen at the bottom should be taken in time. Aquatic plants should be controlled 20-30 cm below the water surface. Weeds should pay attention to prevent withering, stem rot, yellowing, rotten roots, sticky mud, crazy growth and so on. , and timely take corresponding technical measures for processing.

| Step 5 | Do a good job in water quality control

Water quality control is the key. Add water 1 time every 2-3 days in high temperature season, and change water while adding water at high temperature. At the same time, take aerobic measures. In the whole breeding process, the substrate modification and microbial agents are used to improve the substrate and water quality, so as to achieve the purpose of ecological breeding. It is much more effective to check the water quality every three days from May to August, find problems in time and prevent water disasters than to control water disasters with drugs.

I adjusted the water level in time when the spring seedlings came down to the pond. It is necessary to grasp the principle of "shallow spring, full summer and suitable autumn" and adjust the water level in three stages. From March to May, the water depth shall be controlled at 0.5-0.6m, and the deep ditch shall be guaranteed at1m; From June to August, it is controlled at 1.2- 1.5m (the water level can be appropriately deepened in hot season), and it is stable at1.0-165438+1October in September. During the period of crab molting, special attention should be paid to keeping the water level stable, and it is not easy to enter or leave the water to prevent stress reaction.

When changing water, first remove the old water at the bottom of the pool (the water at the bottom of the pool usually flows into a deep ditch, so it is necessary to widen the back ditch, and then pour fresh water from the outer river and change it in 3 14 times. The water exchange rate should be controlled at 1/5 of the pool water, and water should be added in the morning or morning, not in the evening.

Dissolved oxygen in water should be kept above 7.5 mg/L all the year round, pH should be stable at 6.50-8.50, molecular nitrogen should be less than 0.02 mg/L, nitrite should be less than 0.2 mg/L, and hydrogen sulfide should be less than 0.1mg/L. In case of the following situations, it is necessary to change water or take other measures: daily fluctuation range of pH is greater than 0.5, pH is less than 7 or pH is greater than 9. The transparency of the pool water is more than 70cm (whiteboard method) or it is too turbid and less than 20cm (blackboard method); The color of the pool water is obviously darker, the inorganic suspended matter is increased, stable foam appears on the pool surface, there are more organic substances, and the oxygen consumption is increased. Aquatic fish have a floating head and a black bottom.

Observe the color of water in time and determine the physical and chemical indexes of water quality. Drawing lessons from the visual experience of old crab farmers, water quality can usually be reflected by water color, such as good water color such as dark brown, yellow-green, light green and emerald green. And common bad water colors such as white turbid water, clear water, turbid water, oily floating water, dark green, dark brown and soy sauce colored water. The poor water quality is not only intuitively reflected in the color of water, but also reflected in the water quality indicators such as ammonia nitrogen, hydrogen sulfide and nitrite through instrument measurement. If the water quality index changes, it should be adjusted appropriately.