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Net cage fish farming technical points
Dec 12, 2018

Net cage fish farming is a kind of box made of synthetic fiber mesh and other materials, and a large water body for fish farming. It has the advantages of large stocking density, high survival rate, fast growth, short breeding period, low feed coefficient, flexible maneuverability, convenient operation, low investment, quick effect and high economic benefit. It is a good way for farmers to get rich. The main points of its breeding technology are as follows.
First, the water conditions of cage fish farming

(1) The waters of the cages should be sheltered from the wind and the sun is flat, and the water depth should be more than 3m per year, which does not hinder traffic and water conservancy facilities.
(2) The water surface is relatively wide, the water level is balanced, and the water flow rate is below 0.2 m/s.
(3) The water quality is fresh and there is no pollution. For the culture of carp, the cage of squid should choose the water with more water quality.
(4) It is best to be close to the village to facilitate management.

Second, the structure and device of the cage (a) the structure of the cage
1. The composition of the cage: The cage consists of three parts: the box, the frame and the buoyancy device.
The box body is the main body of the cage fish culture, and is made of a mesh piece woven into a different mesh by a material such as a vinyl wire. The frame is a bracket for hanging the box, and is made of materials such as bamboo, wood, steel pipe, and plastic pipe. Buoyancy devices include fishing plastic floats, glass balls, oil drums and car tires.
2. The shape of the cage: there are cuboids, cubes, cylinders, etc. Currently, there are more cuboids.
3. Size of the network: The size of the network of the network box is determined by the object of stocking. The cages for stocking summer flowers require the nets to be below 1.1cm, and the nets of the fish species are stocked, the nets are 2.5 to 3cm, and the cages of the adult fish are 3 to 5cm.

(2) Equipment for the cage

According to the form of the cage device, it can be divided into a fixed cage, a floating cage, and a sunken cage. The specific installation method is as follows: four bamboos or firs (10-12 cm in diameter) are used according to the length and width of the cage, and the four-sided box of the cage is suspended, and the frame is made of 12-gauge wire, and the cage is filled with oil drum or automobile inner tube. Wait for the float, and use the four-angle hanging stone or the red brick at the bottom of the cage as a sinker to straighten the bottom of the net. Use a thicker vinyl rope or steel cord to tie the corner of the cage to the stump on the shore. The rope can be long or short to move the cage. If multiple cages are arranged, the cages are scattered as sparsely as possible, and the vertical and horizontal distance between the boxes and the boxes is 10-20 m.
Third, fish stocking

(1) Stocking types
The fish selected for cage culture must have: (1) fast growth and short breeding cycle; 2) the bait requirements are not strict and easy to solve; (3) the meat is fresh, popular in the market and high in economic value; (4) The source of fish species is easy to solve; (5) It has wide adaptability, strong disease resistance and easy breeding.
At present, most of the rural areas use cages to raise grass carp and carp, which are more common with squid, tilapia, carp and carp. In large and medium-sized reservoirs, most cages are bred (2) stocking specifications, carp species, and local Stocking to solve the problem of stocking fish on the surface.
General fish species cages, stocking specifications are more than 5cm, should not be small. In adult fish cages, the weight of grass stocks is generally 100g or more, and about 250g is better. The weight of the carp and the tail is more than 50g. The specifications of the fish species are as neat as possible.
(3) The stocking density and the stocking density should be determined according to the size of the cage, the quality of the fish, the source of the fish, the specifications of the cultivation and the level of the farming technology. Breeding cages, general waters stocking carp, carp summer flowers 50 ~ 200 tails / m3, the fertilizer water quality can be 200 ~ 300 / m3, out of the box specifications up to 13cm, the proportion of squid can account for 50% of the total %~70%. Adult fish cages, stocking 20 ~ 100 / m3, the seeding weight is generally calculated according to the meat ratio of 1:5, that is, the cage that requires 500kg of adult fish must be placed 100kg fish species, and requires a foot. Its proportion is mostly grass carp, and it is matched with about 10% cockroach, cockroach or tilapia.

(4) Delivery time
Breeding cages for fish species, stocking summer flowers at the end of June and early July to extend the growing season. The cage fish species that breed 2nd-instar fish and adult fish should be released before the winter solstice to the beginning of spring. It is best to choose sunny days, when the water temperature is about 10 °C, it can not be placed during freezing to prevent frostbite. (5) Precautions for fish species entering the box
Before the water tank is inspected, it is necessary to carefully check whether the net clothing is damaged, and ask the fish to launch the water 10 days before the box is put out, so that the net box is softened and some attachments are generated to reduce the friction damage after the fisherman box. Into the box fish species require neat specifications, physical fitness, disease-free and harmless, it is best to cultivate on the spot, avoid long-distance transportation. Fish species should be stretched before entering the box to adapt to the cage environment. Grass carp species should be vaccinated and immersed and sterilized with drugs. The operations should be carefully and accurately calculated into the box when stocking. Because the fish that have just been placed in the cage can not adapt to the new water environment, the fish often jumps or swims around the cage. It is necessary to put a small amount of tender grass in time to reduce the turmoil after entering the box. .

Fourth, feeding management
(I) Daily management The quality of daily management work not only affects the output, but also directly affects the success or failure of cage fish farming. To this end, the following tasks should be done.
1. Regularly check the cages: cages are most afraid of nets and escape fish. Generally, they are checked once a week. Generally, in the weather with small wind and waves, check in the morning or afternoon. Pay special attention to the nets under the surface of 30~40cm. This place is often hit by the impact of floating objects, as well as enemy attacks such as water rats, it is easy to break the fish. After checking the net body, check the bottom net and the points where the net clothes are connected with the net frame. The net clothing in these places is easy to wear or tear and form a loophole. Any seams should be carefully inspected to prevent loosening. In case of flood impact, obstacles are caught or the fish in the cage is abnormal, it is necessary to check the cage in time, find loopholes, and make up in time.
2, wind and wave protection: Before the flood in the storm period, check whether the frame is firm, strengthen the anchor rope and wooden stake, prevent the cage from sinking and being washed away by the flood to prevent the object from being hit by the floating object.
3, timely shifting: When the water is dry, the water level is falling, the net clothing has the danger of being stranded. The cage should be moved to the deep water level; before the flood peak arrives, the cage should be moved to the slow flow to avoid the flood shock. When the polluted water quality enters the tank, the cage should be moved to a safe and suitable place in time.
4, to prevent fierce fish and other enemies bite the cage to bite the fish: If you find squid, crab, turtle, mouse bite the cage, you should take appropriate protective measures.
5. Adhere to the washing of the box: After the cage is launched, the algae such as green mud and moss are easy to adhere to the mesh, affecting the exchange of water, increasing the weight of the cage, corroding the mesh material, and lurking the fish pathogen, seriously affecting the breeding effect. Therefore, it is necessary to promptly remove the residual bait and dead fish in the cage, and insist on cleaning the cage regularly. The cleaning method is as follows: lifting the net clothes, using materials such as bamboo sheets, and manually pulling the net pieces to bounce off the attached objects or washing them with artificial rubbing. Conditional places are flushed with a high pressure water jet. Bio-clearing methods can also be used to breed and attach algae fish in cages, such as squid, tilapia, squid, squid, squid, etc. This method can save labor and money, and increase fish. Yield.

(2) Scientific feeding of bait Feeding is the main measure to increase the yield of intensive fish farming. The quality of feed and feeding technology are the key factors affecting aquaculture production and economic benefits. To this end, we must feed scientifically and do the "four-set" feeding.
1. Qualitative: The feed to be fed is fresh, palatable and non-toxic. Generally, the rotted and degraded feed should not be fed. Some feeds can be immersed in the drug to prevent fish disease.
2, quantification: Quantitative is based on the size of the fish, in different seasons, time and moderation of reasonable feeding. When the water temperature reaches 7 °C or above, you can feed a small amount of fresh grass. As the temperature rises, gradually increase the feeding amount. From July to September, it is the peak of feeding of fish, and it is also the "storm period" of grass carp. Fish eat well. As for the daily feeding amount, it is necessary to be flexible according to the feeding, weather, activities, etc. of the fish. After feeding, it will be eaten very quickly. It is necessary to increase the feeding amount appropriately. If you can't finish eating for a long time after feeding, you should reduce the amount of feeding. If the weather is sunny, you should cast more. If you are hot and rainy, you should cast less. The fish is healthy and active. When you are normal, you should invest more, and you should invest less or not.
3, timing: generally 2 times a day, that is, 8 to 9 am, 16 to 17 o'clock in the afternoon; 7 to 9 months of fish growth season, can be fed 3 times a day, 8 to 9 am, 14 to 14 in the afternoon At 15 o'clock, it is 18 to 19 o'clock in the evening.

4. Positioning: Feeding the concentrate must set the bait table in the cage to prevent waste, and it is also convenient to check the feeding situation. It can be made of sieve pad gauze or smooth bamboo raft, suspended in 40cm water.
(3) Prevention and treatment of fish diseases The cages are installed in the micro-flowing water body, and generally have a higher survival rate than the ponds, but the fish population in the cages is relatively dense, and it is easy to spread and spread once the disease occurs. Therefore, in addition to scientific feeding, careful operation, enhanced observation, prevention of fish injury, reduction of pathogen transmission, and daily management, we must also do a good job in drug prevention. Before the fish species are put into the plant, the grass carp species should be injected with the immunization. In the lower case, use 1g of bleaching powder to dissolve in 100kg of water, dissolve the fish species for 10~15min, or dissolve the fish with 2~4kg in 100kg water, and dip the fish for about 10min. It can also be immersed and disinfected with drugs such as malachite green, potassium permanganate and trichlorfon. After the fish is put down in the box, it is hung with bleaching powder or copper sulphate. Before the onset of the disease season, it is fed with sulfonamides, garlic, etc., and combined with the net to check and wash the fish with drugs. It is necessary to find the right medicine for fish disease and treat it promptly.

(2) Knowledge of cage fish culture
Net cage fish farming is a scientific method of raising fish on the basis of temporary maintenance. It is a box that is assembled into a certain shape by using a mesh piece, and is arranged in a large water body, and the water body inside and outside the cage is exchanged through the mesh to form a living water environment suitable for fish living in the cage. High-density culture of fish or intensive commercial fish can be carried out using cages. The cage fish culture method is characterized by maneuverability, flexibility, simplicity, high yield, wide adaptability of waters, and has a broad development prospect in China's sea and freshwater aquaculture industry.
First, the characteristics and key of cage fish farming
(1) Characteristics of cage fish culture
  1. Net cage fish farming can make full use of rivers, rivers, lakes, reservoirs and other natural water bodies and their bait to develop fish farming. It can breed both fish and fish. Especially in areas lacking ponds, it is possible to use the large water surface to set up cages to cultivate fish species on the spot, and to raise adult fish on the spot, which has a positive effect on improving the survival rate and yield of fish farming.
  2. Net cage fish can be intensively cultivated at high density, and the output per unit area can be several times higher than the pond and hundreds of times. The reason is: cage fish farming is actually using the superior natural conditions of the large water surface, comprehensive small water body intensive measures to achieve high yield. During the aquaculture process, the water inside and outside the cage is continuously exchanged, taking away the fish excrement in the cage and the residue of feeding the bait, bringing oxygen and plankton to keep the tank dissolved high. Oxygen, so in the case of high density of fish in the cage, there will be no shortage of oxygen and water quality, and the feed organisms required for the carp and carp cultured in the cage will be continuously supplied. In addition, the fish are kept in the cage, and the harm of the enemy organisms is avoided, and the fish disease can be found in time to ensure a high survival rate and an excellent recovery rate.
3. Net cage fish farming has the advantages of maneuverability and flexibility, and can be invested in batches and gradually developed. Because of easy feeding and management, easy fishing, the water body of the cage can be moved at any time if the environment is not suitable, so it is also called nomadic fishery.
(2) The key to cage fish farming
  1. Choose a cage that is rich in natural bait and has a certain water flow.
  2. Choose the appropriate cage structure and installation method. Including the shape, size, arrangement and box distance of the cage.
3. The stocking of fish, specifications, density and polyculture ratios should be determined according to water conditions in order to give full play to the potential of water production.
4. Do a good job in feeding and management of feeding, anti-escape, disease prevention, anti-vulnerability, etc., especially to keep the wall of the cage clean, to prevent clogging of the mesh, and to affect the exchange of water.
Second, the structure and device of the cage
There are many forms and structures of cages. In practice, the principle of not losing fish, being durable, saving labor and materials, facilitating water exchange and convenient management is the principle.
(1) The structure of the cage
  1. Net cage composition
It consists of a box, a frame, a float, a sink, and a fixed facility.
(1) Box: It is made by stitching and stitching the mesh according to a certain size. At present, the most common application is polyethylene mesh, which has the advantages of high strength, corrosion resistance, low temperature resistance and low price. There are four kinds of processing techniques for mesh: 1 polyethylene stranded yarn hand-knotted mesh. The advantage is that it is flexible and durable. Disadvantages are nodules, easy to scratch the body of the fish, with more materials, and poor water filtration; 2 non-extended no nodular mesh. The process is fast, material-saving and cheap, but the lateral tensile force is poor and easy to break; 3 extends the no-nodule mesh. Its tensile strength, softness and light weight are 3/4 lower than the cost of cages with nodules; 4 polyethylene warp-knitted mesh. The knot is smooth, does not hurt the fish body, the mesh is not shaped by the stereotype, the box is soft, easy to suture, and it is not easy to open the hole to escape the fish, and the cost is low.
(2) Frame: It is a bracket for hanging boxes, which is usually made of bamboo, wood, steel pipe, plastic pipe and other materials. Fixing the box on the frame keeps the box open and shaped.
(3) Float: It is a device for floating the cage on the water. A foam made of foam and hard blow molding is used, or a glass ball or an iron bucket is attached to the frame as a float. The bamboo and wooden frames act as a float while supporting the box.
(4) Shenzi: It is a device that makes the bottom of the cage sink in the water. Porcelain sinkers are generally used, and stones, cement blocks, etc. can also be used. Conditional available steel tubes with a diameter of 2-2. 5 cm can be used for both the bottom net and the sink.
In addition, the position of the cage should be fixed with iron anchors, or the cages should be supported by cement piles and bamboo piles.
  2. Cage shape
   There are rectangles, squares, cylinders, octagons, and the like. At present, there are many rectangles commonly used in production, followed by squares, because of its convenient operation, large water area and convenient production.
3. Size of the cage
The minimum cage area is about 1 square meter. Usually, the cage of 1-15 square meters is a small cage. The cage area is 15-60 square meters for medium-sized cages, and the large cages are 60-100 square meters. The bigger one is 500-600 square meters. Generally speaking, the area of the cage should not be too large, too large for inconvenient operation, and resistant to wind. However, the output of too small cages is high, but the cost is high. At present, most of the cages of 10-30 square meters are used, namely 7×4 meters, 5×3 meters, 3×3 meters, 3×4 meters and so on.
4. Cage height
The height of the cage is determined by the depth of the water body and the vertical distribution of the plankton. At present, the use of high is between 1.5-2.5 meters. The water body can also be used in cages with a height of about 2-4 meters. However, the distance between the bottom of the cage and the bottom of the water should be at least 0.5 meters, so that the bottom waste is discharged out of the cage.
5. Mesh size
The size of the cabinet mesh should be determined according to the breeding object, in order to save material as much as possible, and to achieve the highest exchange rate of the cage water body. The mesh is too small, which not only increases the cost of the cage, but also affects the exchange of water flow; the mesh is too large and there is a phenomenon of escape from fish. usually

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