In order to develop and utilize underground hot water resources and develop special aquaculture, Xiangtan County undertook the Spark Program “Groundwater Hothouse Bream Technology Development†issued by the Hunan Provincial Science and Technology Commission in 1998. Piquanquantan hot spring (flow rate 0.32m3/s) is located in Biquan Village, Jinshi Township, with a constant temperature of 19°C. Carp was introduced by Fujian Putian Breeding Company. The aquaculture area is 10,560m2, and 800,000 European seedlings are planted, producing 鳗121t, and the total planting rate is 80%. The average discharge specification is about 200g, and the total output is planted to 6.776 million yuan, and the production cost is removed by 4.841 million yuan. With a net income of RMB 1.935 million, it completed the project's expected target tasks. The relevant technologies are summarized below.
1 Dianchi Design and Construction
Dianchi Lake is located in a low-lying paddy field 200 to 300m away from the outlet of the hot springs. It rents a site of 26,680m2 and builds a breeding pond of 10,560m2. The ratio of seedlings and ponds to ponds is 1:3, ie, the seedling pool is 2640m2. Pool 132m2; Chengyu Pool 7920m2, 220m2 per pool. The pool shapes are rectangles with little difference in length and width. The pool angle is octagonal. The structure of the pool wall and the bottom of the pool is red brick concrete. The depth of the seed pool is 1.2m, and the depth of the pond is 1.5m. Each tank is equipped with 2 waterwheel aerators. All Dianchi Lakes are tied with bamboo and wood, covered with black Plastic Film as a heat shading device.
2 Rice seedlings
Before stocking, the seedlings shall be soaked in 50g/m3 bleach and 2mL/m3 of trichlorfon clear pond for 1 week, thoroughly disinfected, cleaned and used.
The size of the seedlings to be placed is 3,000 to 5,000 pieces per kilogram, and the body color is darker and the body surface has no traumatic strong white. Due to the long period of time it takes for the European eel to go fishing, holding and transporting it to the breeding farm, the seedlings are of weak constitution, poor adaptability to the environment, and are vulnerable to infection by various pathogens. Therefore, measures should be taken to minimize the “contrast†of the environment. "And disinfect carcasses. The method is to leave the seedlings in an oxygenated bag and put it in a pool so that the temperature difference with the environment gradually approaches the same. The salinity of the pool water is 0.5% to 0.7%, and the water depth is 25 to 30cm. The seedlings enter the pool and adjust the buoyancy, flow velocity and direction of the waterwheel. The leaflets of the trolley just touch the water surface, which can make the whole pool water rotate better. On the second day after emergence, 15 to 20 mL/m3 formalin and 1 to 1.5 g/m3 furazolidide bath for 1 d were used. On the third day, the water was changed to salt, and the salinity in the water was controlled at 0.2% to 0.3%. Stocking density: 500-800 white mites are stocked per m2, 300-500 black baits are stocked, and 30-50 fish are stocked.
3 Feeding management
3.1 Lures
After the water temperature has risen to 22°C, the whole pool is washed and disinfected with silkworms, 3 times a day, and the daily feeding amount is 2% of the weight of the carp. The remaining bait is fished on the same day and it is continuous for 2 to 3 days. Sprinkle the waterwheel when it spills. Then, the electric light above the bait-feeding platform was irradiated to attract food, and the silk cocoon gradually concentrated on the bait station, so that the food was lured for 3 to 5 days. During the lure process, the bait station slowly rises to the surface of the water, and the depth of the pool water also increases. After the completion of domestication, it was switched to “eat less meals†and the daily feeding was performed 3 times at 6 hours, 14 hours and 22 hours.
3.2 Feed and Feed
After the white bait was fed on the silkworm 25-35d, the white bait was used to feed the bait. The ratio of the first feed with the bait and the silkworm was 1:2, and the proportion of the silkworm was gradually reduced within 5 days. Feed bait. When the weight of the seedlings reached 2g or more, use special baits for black chicks and use 1 meal before switching to use. The first black bait and white bait were mixed and fed in a 1:2 ratio. The first day was changed to 1:1, and the third day was changed to 2:1. On the fourth day, pure black bait was used for feeding. From black cubs to young cubs, and from cubs to pupa, special baits are used in each stage. The materials are changed according to the above method.
Add a proper amount of various vitamins to the compound feed to ensure complete nutrition, and at the same time increase the viscosity to prevent loss, resulting in deterioration of water quality, generally transferred into a hard paste feeding.
From seedlings to clams, the amount of feed was strictly controlled, and the degree of feeding was completed after 30 minutes (80% of all food was eaten). According to the weight of ticks, the feeding amount of white and black piglets was calculated as 1% to 2% of their body weight, and that of young and adult piglets was 1.5%.
Due to the different growth rates of European oysters, there is a phenomenon that large oysters eat oysters during the adult stage. Therefore, we should regularly select stocking, so that the size of the carp is relatively consistent feeding in the same pool, under normal circumstances, one and a half months to two months of separation and nutrition once. Carefully and cautiously when selecting and maintaining the stocks to reduce the carp's trauma, disinfect immediately after sorting to prevent germ infection.
3.3 Water Quality Management and Disease Prevention
Maintaining fresh water is not only the basic requirement for aquaculture in Europe, but also an important measure to prevent its occurrence. Whether water quality management is appropriate or not is one of the keys to the success of European eel breeding. The development of this project mainly adopted the following measures in water quality management and disease prevention and control. The first is to implement closed management of water sources. Some of the hot spring water flow will be used by local villagers to live, then the outlets will be closed, and all the water diversion pipes will use ramps to ensure that the water sources are free from pollution. The second is diligent water injection, diligent drainage, and the constant flow of water in Dianchi Lake. Because the dissolved oxygen in groundwater is not enough, and the closed flow is imposed, it is very important to increase the oxygen in the water body. Oxygen is used to start the aeration machine throughout the day. The third is the tour patrol pond. Every day, the patrol ponds pay attention to the situation of the squid after eating. At night, the patrol pond should pay attention to whether there is a floating-head threat. Daily cleaning of Dianchi Lake, cleaning. The fourth is to take regular preventive measures such as spraying potassium permanganate, bleaching powder, strong chlorine extract, quicklime, and salt water baths to ensure prevention of disease. Fifth, the right medicine, early treatment. Once the disease is found, stop feeding, use Chinese herbal medicine, and treat the disease.
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