Jintan City, Jiangsu Province discussed the technology of reasonable combination of multiple species in river crab breeding ponds, and successfully proposed the "631" pond high-efficiency ecological breeding model, which mainly uses river crabs and scientifically mixes green shrimps, mandarin fish, and green shrimps. Red-mouthed crucian carp, heterotrophic silver carp, bighead carp, silver carp and other aquatic species have been cultivated to achieve a per-acre production of 60 kilograms of river crabs, 30 kilograms of green shrimps and 100 kilograms of high-quality fish.

(1) Breeding conditions

① Location selection: The breeding pond must be close to the water source, with easy access and drainage, abundant water source, fresh water quality and no pollution, in line with the national fishery water standards, and adjacent areas No source of pollution. It also requires convenient transportation and guaranteed power supply.

②Pond transformation: The breeding ponds are mainly on the beach surface, and the water in the pond is relatively shallow. There should be a ditch for raising crabs in the pond, and there should be cover on the beach. The area should be 20 to 30 acres, the depth of the pond should be about 1.5 meters, the slope ratio should be 1:3, and 5 centimeters of silt should be kept at the bottom of the pond.

③Drainage and irrigation facilities: The drainage and irrigation facilities of the crab pond are required to be perfect, so that the water can be filled in and drained out. If the pond water cannot be drained, it will cause inconvenience to the later crab fishing and drying in the pond. The inlets and drains should be tied tightly with screen tissue, and curved anti-escape nets should be installed for protection.

④ Anti-escape facilities: Anti-escape materials require a smooth surface, making it difficult for river crabs to climb, and are durable, resistant to aging, widely sourced, simple to construct, and easy to repair. Calcium plastic boards or anti-escape nets are usually used Made into anti-escape facilities.

(2) Preparation before stocking

① Pond cleaning and disinfection: drain the pond water in winter, freeze and dry for one month, and remove excess silt. After the pond cleaning work is completed, add 10 to 20 centimeters of water, use 150 to 200 kilograms of quicklime or 2 kilograms of tea meal per acre (use 40 kilograms of salt water with a concentration of 2.5%, and soak for 2 hours). Sprinkle the entire pond and plow the bottom the next day. Add water to soak the mud for 2 to 3 days, then drain the pool water, flush and wash the pool twice.

② Planting aquatic plants: After disinfecting the pond for 7 days, apply 50 to 100 kilograms of bio-organic fertilizer per acre to improve water quality. Use composite aquatic plant planting methods for aquatic plant cultivation. The whole pond is dominated by Elodea, and the stems are cut and planted in sections. Plant Hydrilla verticillata, Vallisneria and other submerged plants in the middle of the Elodea, keeping the aquatic plant coverage in the entire pond at about 50%.

③ Set up a temporary breeding area: Use a net to form a circular or rectangular temporary breeding area for river crabs in the pond. An anti-escape film is posted on the net. The area accounts for about 20% of the water surface of the pond for temporary crab breeding. kind.

④Transplantation of snails: Before and after the Qingming Festival, 200 to 250 kilograms of high-quality live snails should be released per acre. From July to August, 150 to 200 kilograms of snails are released per acre.

(3) Stocking mode

Reasonably arranging species with different ecological niches and scientifically mixing and breeding them is an effective way to achieve ecologically efficient cultivation of crab ponds. The main requirements and practices are:

① Stocking self-bred crab species: Properly stocking local self-bred crab species is the prerequisite and guarantee for achieving a simultaneous increase in crab quality and yield. Crab species require high-quality local self-bred crab species from the Yangtze River system with good structure, sound limbs and no disease. The size is 100-200 crabs/kg, and the stocking rate is 600 crabs/acre. The crab species are first placed in a temporary breeding area for intensive cultivation. After May, the freshwater shrimp fishing is basically completed, and then the whole pond is released.

② Rotation of fresh shrimps: Crab ponds are relatively idle before May, mainly for the growth of aquatic plants. Using this stage to raise fresh shrimps in rotation can better improve the overall efficiency of the pond. The specific method is: after the pond is cleaned and disinfected (that is, from January to February), 10 kilograms of shrimp seeds with a size of 1,000 to 2,000 shrimp/kg per acre are placed.

③ Raising mandarin fish and red catfish in nests: In order to make rational use of small miscellaneous fish at the bottom of the crab pond, 5 to 7 centimeters of intensively cultivated mandarin fish species are released per acre from the end of May to the beginning of June. 30 fish; the red catfish feeds on small miscellaneous fish in the middle and upper layers and extruded pellet feed, etc., and is omnivorous. If the size of the seedlings is too small, it is easily preyed on by mandarin fish. From the end of April to the beginning of May, every acre should be stocked 20 large-sized cock-billed red catfish, 10 to 15 cm.

④ Reasonable combination of silver carp, bighead carp and heterogeneous silver carp: from February to March, stock 10 silver carp and white silver carp per acre, with a stocking specification of 15 to 20 fish/kg per acre. Heterobred silver crucian carp species weighs 5 to 7 kilograms. While obtaining part of the production, the heterotrophic silver crucian carp can also lay eggs and reproduce, providing sufficient and palatable bait fish for mandarin fish.

(4) Feeding and management

① Feeding: Since there are many varieties of pond culture and the biological load capacity is large, scientific and reasonable feed feeding should be carried out for different cultured species. Feeding is key. The specific requirements are to achieve "overall consideration and individual emphasis."

First, during winter rotation, shrimp seeds are stocked outside the temporary breeding area. When the water temperature rises to 10°C, 100 to 150 kg/acre of organic fertilizer is applied to the entire pond to cultivate plankton and benthic organisms and provide natural active food for freshwater shrimp. At the same time, insist on feeding special pellet feed for freshwater shrimp, and the feeding amount is calculated as 5% of the body weight of the shrimp in the pond.

Second, when the crab species are in the temporary breeding area, in order to strengthen their cultivation, animal feed such as chopped fresh small fish is fed every day, with a feeding amount of 1 kilogram per acre. When animal feed such as small miscellaneous fish is insufficient, river crab pellet feed should be supplemented appropriately.

Third, in May, the freshwater shrimp fishing basically ended. The temporary breeding area for crabs was dismantled and the whole pond was free-range. Since the heterotrophic silver crucian carp was stocked, in order to prevent the heterotrophic silver crucian carp from competing with the river crabs for food. , before feeding the river crab bait, feed the heterotrophic crucian carp feed first, and then feed the river crab feed 2 hours later to ensure the normal feeding of the river crab. There are three types of river crab bait: plant feed, animal feed and compound feed, in the form of pellets The main food is bait, and artificial feeding management is carried out in accordance with the feeding principles of "front and rear essence, middle green, meat and vegetable combination, and green and essence combination" and the scientific feeding method of "four determinations and four looks". In mid-June, the ratio of animal and plant food is 60:40; from late June to mid-August, the ratio of animal and plant food is 45:55; from late August to mid-October, the ratio of animal and plant food is 65: :35. The daily feeding amount is about 1% of the crab body from March to April, 5% to 8% from May to July, and more than 10% from August to October. And according to the weather, water color, feed more on sunny days and feed less on cloudy and rainy days. During the high-temperature season, two changes are implemented, that is, the feeding location is changed from shallow water to deep water, and the feeding of high-protein feed is changed to low-protein feed to ensure that the river crabs spend the summer safely. When the river crabs are sexually mature, due to the increased activity of the river crabs , the amount of food eaten in the afternoon is reduced, and the afternoon feeding is changed to the morning feeding to prevent the crabs from weakening.

Fourthly, the red-billed catfish mainly feeds on small wild fish in the upper and middle layers of the water body. In order to supplement the deficiencies of wild fish and ensure the normal growth of the red-billed catfish, puffed red-billed catfish should be supplemented. The feed was mainly domesticated at first, using surimi and extruded feed at fixed points, in small amounts and many times. Later, the amount of surimi was gradually reduced until extruded feed was used. The daily feeding amount should be consumed within 2 hours of feeding, and should be fed at the same time as river crab pellet feed.

Fifth, because the pond is stocked with heterotrophic silver crucian carp, and other small wild fish spawn and reproduce, it can basically meet the growth needs of mandarin fish. If the bait is insufficient, the heterotrophic silver carp needs to be supplemented. Summer flowers of crucian carp, flowered silver carp, and white silver carp are provided for mandarin fish to eat.

② Water quality and water level adjustment: In terms of water quality adjustment, the water quality must be "fresh, lively, tender and refreshing". Specifically, the dissolved oxygen is maintained above 5 mg/L, the transparency is above 40 cm, the pH is around 7.5, and the ammonia nitrogen is below 0.1 mg/L. Water should be injected once every 5 to 7 days, and 10 to 20 centimeters of water should be injected every day during high temperature seasons. Especially during each molting period of river crabs, water should be injected frequently to promote the normal molting growth of river crabs. When the water quality of the whole pond is good, use the self-purification function of aquatic plants, snails and other organisms to implement zero emissions. Pay attention to the use of the aerator in the crab pond. During the high temperature period, the aerator is frequently turned on at noon, after midnight and before dawn on sunny days, and on cloudy and rainy days. The machine is turned on around the clock to ensure the normal growth of river crabs, fish and shrimp, and that the crab pond does not lack oxygen.

In terms of water level adjustment, the water level is adjusted in three stages according to the principle of "shallow in the front, deep in the middle, and stable in the back". The water depth is controlled at 0.5-0.6 meters from March to May, 1.2-1.5 meters from June to August, and stable at 1-1.2 meters from September to November. The water temperature for river crab growth is 15-30°C, and the optimal growth water temperature is 25-25°C. 28℃. When the water temperature is above 33℃, they stop feeding and are in a semi-coma state. The air temperature and water temperature are low in the early stage. The shallow water level is conducive to the rapid increase of the water temperature of the breeding water body, so that the river crabs and green shrimps can enter the normal feeding state and molt as soon as possible. grow. In the mid-term high temperature season, deepening the water level will help lower the water temperature, allowing river crabs to feed and molt normally. In the later period, stabilizing the water level at a moderate level will help maintain normal water temperature, allowing river crabs to have a stable water environment for weight gain, fattening, and smooth growth.

③Daily management: Observe the molting growth of river crabs, diseases and enemies in combination with feeding, check the water quality of water sources, clean the breeding environment, check anti-escape facilities, and repair cracks in a timely manner.

④ Disease prevention and control: Follow the principle of "prevention first, combine prevention and treatment", adhere to the combination of ecological regulation and scientific medication, actively adopt pond cleaning and disinfection, plant aquatic plants, self-breed crab seeds, scientific feeding, Comprehensive technical measures such as regulating water quality to prevent and control the occurrence of diseases. Pay attention to the application of micro-ecological preparations, adopt the method of "combination of top and bottom", and spray the whole pond with microbial preparations such as photosynthetic bacteria and EM every 7 to 10 days to improve the water quality. Use biological substrate feed to improve the immunity of river crabs. Since biological bacteria consume oxygen, the aerator should be turned on when splashing biological bacteria to prevent hypoxia in the pond. Drug prevention should be done in advance, and the focus should be on "prevention and prevention" throughout the year. There are three stages of "control and protection". From the end of April to the beginning of May, use medicine to kill ciliates once. After an interval of 1 to 2 days, use bromochlorohydantoin or iodine preparations to disinfect the water body, and use 1% Chinese herbal medicine to make granular bait. Feed continuously for 5 to 7 days, and do preventive work to prevent the occurrence of diseases. Before the high temperature comes after the rainy season, kill ciliates, disinfect the water body, and take bait orally to control the occurrence of diseases during the high temperature period. In mid-September, water disinfection and oral administration of bait will be combined to kill ciliates. At the same time, feeding will be strengthened to enhance the crabs' physical constitution and disease resistance, ensuring that the crabs can successfully survive the final weight gain and fattening period.

(5) Sales and transportation

From October to November, fishing is mainly carried out with nets, light trapping, and dry pond catching as a supplement. The caught river crabs are put into covered nets Temporarily raised in an anti-escape cage. The location of the cage should be selected in a large pond with fresh water quality. The temporary breeding area uses a submersible pump to circulate water to accelerate the flow of water and increase dissolved oxygen. After 2 hours of temporary cultivation in the cage, the mud will be spit out and filtered, and then the specifications will be divided. Separate into male and female, packed in separate bags, affixed with trademarks, insulated and transported to the market for sale.