Pond technology research, perfect culture technology has high nutritional value of freshwater grouper mandarin fish
Zheng Xiaoyu and so on
Spotted mandarin belongs to the order Perch, family, subfamily Mandarin, Mandarin, also known as rock mandarin, because of its round body like a barrel, so it is called bamboo tube mandarin. Because of its tender, delicious meat and high nutritional value, it has the reputation of "freshwater grouper" and is deeply loved by consumers. The spotted mandarin fish belongs to the demersal fish, can live in rivers and lakes, mainly distributed in the water systems south of the Yangtze River, like to inhabit the fresh water quality, there is a micro-flowing water environment, to eat small fish and shrimp. In recent years, with the sharp increase in demand in the domestic and foreign markets, the scale of spotted mandarin farming continues to expand, this paper from the perspective of intensive pond culture to carry out relevant technical research, aimed at improving the breeding technology, in order to improve the economic benefits of breeding spotted mandarin fish farming, reduce the cost of breeding, provide relevant technical reference.
1 Materials and methods
1.1 Pond selection
The test ponds are located in Wujin, Changzhou, with an average pond area of about 2 000 m2, a total of 58 ponds, with a total area of 210×667 m2. The bottom of the pond is flat, the silt thickness does not exceed 10 cm, the water depth is about 1.6 m, the pond is free of water seepage, and the nearby water source is sufficient and pollution-free. The pond is easy to drain and the drainage outlet is 15 to 25 cm lower than the surrounding area, which is convenient for dry pond fishing. The inlet is set in the upper part of the pond, with a polyethylene mesh cloth of about 40 mesh, the length of the mesh bag is not less than 1.5 m, to avoid falling off when entering the water, the drainage outlet is set at the bottom of the pond, and the 20 mesh polyethylene mesh is used to prevent the fish species from escaping when draining. The pond is equipped with common equipment such as aerators, submersible pumps, etc.
1.2 Pond cleaning
Spotted mandarin fish prefer to inhabit fresh water and hard bottom water, 1 month before stocking pond renovation work, strengthen the pond slope, pond embankment, remove weeds around the pond, drain the pond water, after 1 week of exposure, fill with new water 5 to 10 cm, and then sprinkle the whole pool with quicklime 250 kg/667 m2 with water for disinfection. One week before the stocking of fish fingerlings, the pond water body is replaced and fertilized to cultivate the phytoplankton and plants in the culture pond, improve the overall environment of the pond, and provide good living conditions for the spotted mandarin fry. The water level is about 0.5 m during stocking, and the water level is gradually increased during the culture process, and the depth of each injection is not more than 20 cm, and the depth of the pond water is maintained at more than 1.6 m in the high temperature season.
1.3 Fingerling stocking
Seedlings are selected from individuals with neat specifications, robust physique, smooth body surface, disease-free and deformity-free and good vitality. In late May, fingerlings are stocked at water temperatures of 20 to 26 °C, with stockings of 1 000/667 m2 and fingerling sizes of about 15 cm and 40 to 50 g/tail, for a total of 210,000 stockings. When stocking, the water temperature is first adjusted, and then the fingerlings are put into cages and soaked with 3% to 5% salt water for 5 minutes to kill the parasites on the fish. Finally, the fingerlings are placed in a small area of domestication for pre-domestication.
1.4 Artificial domestication
A corner of the pond is enclosed as a domestication area with a 40-mesh polyethylene mesh sheet, an area of about 8% of the entire pond, a net height of 1 m, and a bottom buried in the mud for 15 cm, supported by bamboo pole piling. Due to the relatively weak feeding ability of the spotted mandarin fish, the "pulp" of the bait fish fed in the early stage of domestication is half-dead, and the amount of feeding is controlled during the entire domestication process, so that the spotted mandarin fry is kept in a moderately hungry state to achieve the purpose of changing its feeding habits. Until the spotted mandarin can get used to eating fresh fish pieces and chilled fish, the fence facilities in the domestication area are removed, and feeding points are set around the pond, until the spotted mandarin can take the initiative to forage at the set point, and the whole domestication process is completed.
1.5 Aquaculture management
1.5.1 Feeding volume and feeding times Sufficient supply of bait is the basic guarantee for the success of breeding. The size of the bait is strictly controlled during the rearing process to allow the mandarin fish to feed. Feed 3 times a day, the daily feeding amount is 5% to 10% of the body mass of the fish, and the bait is fresh wild trash fish, small-flowered silver carp and long-barreled chilled fresh bait fish.
1.5.2 Daily management During breeding, regularly clean the stains on the inlet and drainage filter screens, and check the safety of the tie mouth frequently. The transparency of the water body is maintained at 20 to 25 cm, and quicklime or photosynthetic bacteria (0.3 mg/L) are regularly sprinkled, and the water is injected and drained regularly, and it is adjusted by changing the water. Use the aerator in time to oxygenate in the summer heat to prevent the hypoxic floating head of the spotted mandarin fish. Insist on patrolling the pond once in the morning, in the middle and in the evening, observe the feeding and activity of the fish and the changes in the dissolved oxygen and water quality of the pond, and find abnormal treatment in time. If local piles of spotted mandarin fish in ponds are found, they are evacuated in time to prevent excessive density and local hypoxia and damage caused by fierce competition for bait. Keep a record of weather, water temperature, baiting, disease and fish growth during breeding.
1.5.3 Disease control Disease control is the key to the cultivation of the spotted mandarin fish. In the process of breeding, it is necessary to achieve the principle of "prevention without disease, early treatment of diseases, and combination of prevention and control".
The bait fish is soaked in 3% salt water for 5 minutes to kill parasites and pathogenic bacteria on the bait fish and reduce the disease caused by the bait. If sick and dead fish are found to be fished out in time, the spread and spread of diseases should be strictly controlled.
Parasitic diseases were found, and a combination of copper sulfate and ferrous sulfate (5:2) 0.7 mg/L was sprinkled in the whole tank, once every other day, and 2 times. Bacterial diseases (gills, rotting skin disease, etc.) are sprinkled with a whole tank of 0.3% aqueous trichloroisocyanuric acid solution, used twice, combined with the feeding of oxytetracycline bait, the daily dosage is 25 mg/kg body mass, and the continuous use is 3 to 4 days.
2 Results
A total of 4.2 million yuan was invested in the project, 483,500 yuan in bait, 36,900 yuan in drug costs, 212,000 yuan in labor costs, and 56,200 yuan in miscellaneous expenses, totaling 4,988,600 yuan.
As of November 2018, a total of 54 930 kg of commercial mandarin fish were harvested, the survival rate of culture was 87.2%, the average size was 300 g/tail, the average yield was 261.57 kg/667 m2, the output value was 7.4156 million yuan, the income per 667 m2 was 35,300 yuan, and the benefit per 667 m2 reached 11,600 yuan.
3 Discussion
The results of the test can be seen that the pond intensive culture mode has the advantages of neat specifications, high yield, easy to catch, and significant economic benefits, which is the recommended high-efficiency ecological breeding mode of spotted mandarin, but the requirements in breeding technology are also relatively high, healthy and efficient breeding must first ensure the excellent quality of the seedlings, the selection of high-quality seedlings can improve the survival rate of seedlings, and it is also easy to breed healthy and high-quality spotted mandarin; reasonable domestication methods are particularly important, and scientific domestication can avoid the increase in the bait coefficient caused by excessive or insufficient bait in the breeding process , so as to effectively reduce the cost of breeding; palatable bait can improve the growth rate of fish species, make the size of commercial fish more neat, but also effectively avoid the damage caused by the fish body caused by the competition for food of the spotted mandarin; the "fat and tender" water environment is the key to ecological breeding, to ensure a good water environment can not only provide a healthy and comfortable growth environment for the spotted mandarin fry, but also an important measure to prevent the disease of the spotted mandarin.
Funded projects: Jiangsu Three New Fisheries Project (Y2016-24), Modern Agricultural Project of Jiangsu Provincial Science and Technology Department (BE2018398)