First, water quality regulation
1, change the amount of water
After October, the temperature, water temperature, and water quality tend to be stable. The porthae crab breeding enters the fattening stage. According to the actual situation, a large amount of water can be changed, and large tides can be used to carry out large-scale exchanges, keeping the water quality fresh, and the transparency is about 50cm, which promotes the large intake of the crabs.
2, water quality indicators
The quality of water directly affects the growth and yield of swimming crabs. When swimming crabs live in poor water quality, it is difficult to achieve a predetermined growth effect. To do this, water quality measurement must be made and the water quality of the cultured water should be regulated.
Determination of water temperature: Every morning at 56 o'clock, the water temperature is measured at 23 o'clock in the afternoon. The temperature directly affects the speed of metabolism of the body of the crab, and the temperature is a basis for the amount of feeding.
Determination of transparency: Tested once every afternoon at 23 o'clock. Transparency reflects how much suspended matter in water, including plankton sediment and other organic matter, is an important factor that should be controlled during the growing period. According to the different needs of each growth period of the crab, create different degrees of transparency for it. The later period is more than 40cm. A suitable transparency not only provides the dark secretive environment for the crabs, but also reduces self-mutilation. A large number of phytoplankton and swarf provide abundant feed for the jellyfish, and the shellfish is the favorite food for the crabs.
Determination of pH: Every morning at 56 o'clock and 23 o'clock in the afternoon. The value of seawater is generally around pH 8.1, and the suitable value of the crab is pH 7.89.0.
Salinity determination: The salinity is measured once before and after the water change. The optimum salinity is 25‰30‰.
Dissolved Oxygen Measurements: Daily at 46 o'clock and at 4 o'clock in the afternoon. The level of dissolved oxygen not only directly influences the metabolism of the crab, but also relates to the state of water chemistry and is an important indicator of water quality. Dissolved oxygen is always required to be greater than 5 mg/l.
Ammonia nitrogen and other nutrients: conditions can be measured one day, no conditions measured one week. A small amount of ammonia nitrogen is a fertilizer in the pond, but when it is contained in a large amount, it becomes a poison factor for swimming crabs and other aquaculture animals, and the breeding period should be controlled at 0.5 mg/liter or less. In order to maintain a good planktonic ecology in the breeding ponds, a proper N/P must be in place to facilitate the breeding of beneficial species in the unicellular algae.
Hydrogen sulphide and nitrite determination: One week. The concentration of hydrogen sulfide must not exceed 0.01 mg/l, and the concentration of nitrite must not exceed 0.5 mg/l.
Second, feeding
In the later period of the crab, the requirement for feed protein is relatively high. The determination of the amount of feed should be based on a comprehensive analysis of the stocking density, individual size, water temperature, water quality, and feed quality of the crab. The bait must be put on the bait station or fed along the pool. Do not put it in the ditch and deep water area to avoid the waste of the bait remaining to pollute the bottom of the pool. Feeding is mainly based on high-quality animal feeds, such as fresh wild fish and freshwater shellfish, supplemented by pellet feed. Less investment in high temperature period, less investment in cloudy and rainy days, less investment in shelling, less investment in poor water quality, more crabs in multiple places, more investment in good water quality, more investment in suitable temperature, more investment after shelling, bad water quality Investment, the quality of the bait is not good, and the bottom bait is not cast.
Third, daily management
1. Observe the activity of the crab:
Swimmer crabs are rarely active during the day and most of them are lurking in the bottom of the pool. They frequently come out at night and feed for food along the poolside. Pay close attention to rainy days, foggy days, high-temperature hot weather, low-pressure typhoon weather, and nighttime situations, which are prone to lack of oxygen. Once you find that the swimming crabs are anoxic, change the water immediately, splash the oxygen-enhanced powder, and start the aerator in time. If a large number of swimming pools are found during the day, it should be analyzed from two situations. One may be that the bait is under fed; the other is likely to be a problem with water quality and sediment quality.
2, patrol pool
The early morning and evening patrol pool is a daily basic work for the farmer. He listens to the local weather forecast in a timely manner, pays attention to weather changes, and drains the water in a timely manner after the rain. He pays close attention to changes in the pool water. Always check the feeding condition of the crab. Pay attention to escape prevention and security.
3, growth measurement and pond diary files
The growth of the crab was measured every 1015 days, including the length/width of the carapace, the weight of the carapace, recording, analyzing the growth, adjusting the feeding amount and adjusting the bait mix. Remember the diary of the pond, including weather, water quality testing, feeding, water exchange, swimming crab activities and disease conditions, to prepare questions and accumulate experience.
IV. Disease Prevention
During the breeding process, the crab growers unilaterally pursued economic benefits, giving up or despising the ecological environment protection of the swimming crab ponds. The seedling density was too high to keep up with the nutrition, or overfeeding the live bait exceeded the capacity of the crab pond itself. Some even feed deteriorated feedstuffs, unclean live bait (odor fish, rotten shrimp, gangrene); eventually lead to portine crab malnutrition, pond water eutrophication, water quality deterioration, bacteria, harmful algae, parasites, Toxic substances, such as a large number of twins, cause the occurrence of Swallow crab disease, and even pandemic. The main diseases found in the aquaculture process include vibriosis, crustacean ulcers, severed limbs, ciliate attachment, spore parasites, attachment of diatoms or green algae, unsuggling, and infections of white spot virus disease in shrimp and other diseases. Scientific aquaculture mainly focuses on prevention, focusing on the protection of the aquatic environment; using healthy crabs; reasonable nutrition; scientific feeding, fresh and live bait must be cleaned and disinfected after feeding, do not overfeed Regularly sterilize the body of water and feed it scientifically.
Fifth, receive crab
After entering November, when the crab grows to about 200 grams, crabs can be produced in time according to market conditions. We can use a large mesh trawl to pull out crabs, or nighttime light trapping, catching large and small, and dropping more than 200 grams of female crabs and more than 150 grams of male crabs out of the pool; small crabs that do not meet the specifications remain in the pool. Continue farming, which will be listed in November. Male crabs must all be released before November, and female crabs can be moved into indoor or outdoor deep pools for winter maintenance after December and sold around the Spring Festival.
Sixth, commodity shuttle crab transport method
Grass turf method: The shuttlecock crab tweezers are wrapped in rubber, with the ventrary face down, and put into a straw turf bag soaked in low-temperature seawater. Each layer is covered with a layer of wet seaweed (such as Rattus albus) until Fill grass bags and fasten grass bags. In the long-distance transportation, attention should be paid to maintaining the humidity of the grass bales, and the straw bales can be poured on the way. The turfgrass method is suitable for transport at low temperatures.
Cooling and hibernation method: The crab claws are tied with rubber bands, and 24 degrees Celsius cold water is used to cool the swimming crabs in a short period of time to promote hibernation and put them into a foam plastic box for heat preservation and long-distance transportation. This method is convenient and reliable.
Inflatable method: The shuttle crab crab clinker with rubber band tightly wrapped into the crab, and then put the crab into the shipping container, keep the water temperature 13 °C, oxygenation and transport.
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