The rainbow trout, also known as red tilapia and pearls (next to plush fish), has the advantages of rapid growth, wide appetite, strong disease resistance, and wide salinity, and can be cultured in fresh or brackish water. The scientific and technical personnel of the Bureau of Oceanic and Fisheries of Huizhou City conducted a trial of rainbow trout mariculture in Guangdong Province from April to the end of November 2001, and achieved good economic and social benefits. Maricultured rainbow trout has the advantages of bright body color, delicate meat, and no muddy taste, and is favored by consumers. The test is now described as follows:
I. Materials and methods 1. Ponds Two ponds (18 acres and 23 acres, respectively) are located in the mid-high tide area with smooth pond bottom and sandy bottom. Each pond has two gates, one for seawater and the other for fresh water. Monthly tides can be reached in 20 days. The average annual proportion of seawater is between 1015 and 1025, fresh water sources are available, and the pond water salinity can be freely allocated. The gate can be used to isolate the water from the outside environment. There is a conical screen (40 meshes) on the inside of the gate to prevent fish from entering the wild fish when entering the water. The depth of the pond is 12-2 meters.
2, clear pond disinfection March 16, 2001, the first half of the fish fry, ponds into the water 20-30 cm, and then use quicklime 75-100 kg / mu with water clear pond, kill bacteria and wild fish. On March 24, 50-70 cm of fresh water was injected. Adjust water quality, apply appropriate amount of organic fertilizer per acre, so that the water to maintain transparency of about 25 cm.
3. Putting on seedlings on April 3rd, stocking males with a rate of 95%, robust, non-injury and disease-free, neatly-sized rainbow trout seedlings, specifications 6-10 cm/tail, stocking density of 2000 tails/mu. On April 8, the seedlings have adapted to the new environment, gradually adding salt water to regulate salinity, increasing their salinity by 5 cents each time, stabilizing them for 3-4 days before continuing to increase salinity into seawater, and finally stabilizing salinity at 15 ‰. Between 20 miles. The entire salinity adjustment process takes 15 to 20 days. The survival rate of rainbow trout seedlings is about 95%.
4. Daily management (1) The feed management feed is expanded tilapia, with a protein content of about 30%, with good stability and palatability. Baiting do "time, positioning, qualitative, quantitative", fed 2 times a day sooner or later, the daily feeding accounted for 3% -8% of body weight of fish, and depending on the water temperature, water quality, food intake and other flexible adjustments. The compound vitamins were added to the feed every 2 weeks at a dose of 2 g/kg feed for 3 to 5 days.
(2) In the process of water-cultivation, basically no water is changed in the early stage, and after the high-temperature period comes in June, the amount of water is gradually increased. Generally, the water is changed every two weeks, and each time the water is changed by 1/4, so that the water in the pond Keep light brown or oil green, transparency 25-35 cm, dissolved oxygen above 3 mg / l, pH 72-82, ammonia nitrogen less than 01 mg / l. Change in salinity within 5 inches of each change of water.
(3) Prevention of disease Maintaining good water quality and reasonable nutrition are the key to reduce the incidence of disease. Use 02- 03 mg/L of chlorine dioxide to splash the whole pond once every 15 to 20 days to disinfect the water body.
Second, the results of dry ponds in late November, a total of 30,930 kilograms of rainbow oysters, the output value of 278,370 yuan, deducting feed costs and other production costs, net profit of 103,250 yuan. During the aquaculture process, photosynthetic bacteria and multivitamins were added to the feed fed from pond No. 2 and the aquaculture effect was significant.
III. Discussion 1. Effect of changes in salinity on rainbow trout The rainbow trout grown in seawater ponds was found to grow faster than freshwater rainbow trout during aquaculture. This may be due to changes in salinity affecting the growth of rainbow trout. During the aquaculture process, the water must be changed at regular intervals (keeping the pool fresh and not aging). This will inevitably cause changes in the salinity of the pool water. Although the rainbow trout is a wide-salinity fish, the salinity changes in the pool water make it necessary for body fluids to penetrate. Pressure regulation, this process rainbow trout growth delay.
During the breeding process, when the amount of water changed in the pond was too large and the salinity change was greater than 9 ,, the appetite decreased significantly in the rainbow trout. This process continued for 2-3 days. By comparing the situation of breeding rainbow trout with three cages in the nearby sea area, it was found that when the salinity of seawater in the sea area is greater than 30‰, the growth of rainbow trout is significantly slowed.
2. The role of adding complex vitamins and photosynthetic bacteria in feeds The addition of complex vitamins and photosynthetic bacteria to feeds will help increase the growth rate and survival rate of rainbow trout. This is because:
(1) Photosynthetic bacteria are rich in bacterial protein, vitamins, growth-promoting and disease-resistant factors, which can enhance the body composition of rainbow lice. In addition, photosynthetic bacteria can also secrete various digestive enzymes in the intestinal tract of rainbow trout and promote rainbow trout to feed. Digestion and absorption, improve feed utilization, and promote growth;
(2) Multivitamins are rich in ingredients that promote and improve the physiology of fish.
3. Diseases in the rainbow arid seawater pond cultivation process, fewer diseases, common diseases are enteritis, fish gills, oblique tuberculosis. The main causes are deterioration of water quality, excessive changes in salinity, and malnutrition. Without long-term water changes, water quality deteriorates, ammonia and nitrogen levels in water increase, eutrophication of water bodies, and large numbers of bacteria and parasites multiply, eventually leading to disease outbreaks. When the salinity changes by more than 10 ,, rainbow trout produces strong stress responses. The decline in body resistance has caused diseases; according to studies conducted by the American Soybean Association, the lack of unsaturated fatty acids (EPA and DHA) in marine culture fish will hinder fish development and weaken the body.
In response to the problems encountered in this breeding process, the author considers improving the Rainbow Bohai Seawater pond culture technology from the following three aspects.
(1) When changing the water, the change of the salinity of the pool water should be minimized, preferably within 3 inches;
(2) It may be considered to breed other economic fish and increase the economic benefits of a unit of water. Mixed economic fish need to avoid overlap in feeding habits and put them in reasonable quantities in order to achieve the best fish load or environmental capacity for a unit of water. The economic fishes that can be considered for polyculture include American redfish, squid, flower-tailed pepper oysters, yellow finned oysters, flower pods, etc.;
(3) Strengthen the nutrient deployment of seawater rainbow trout and formulate a feed for rainbow trout cultivation with balanced nutrition and moderate price, which lays the foundation for the development of rainbow trout seawater scale farming.
I. Materials and methods 1. Ponds Two ponds (18 acres and 23 acres, respectively) are located in the mid-high tide area with smooth pond bottom and sandy bottom. Each pond has two gates, one for seawater and the other for fresh water. Monthly tides can be reached in 20 days. The average annual proportion of seawater is between 1015 and 1025, fresh water sources are available, and the pond water salinity can be freely allocated. The gate can be used to isolate the water from the outside environment. There is a conical screen (40 meshes) on the inside of the gate to prevent fish from entering the wild fish when entering the water. The depth of the pond is 12-2 meters.
2, clear pond disinfection March 16, 2001, the first half of the fish fry, ponds into the water 20-30 cm, and then use quicklime 75-100 kg / mu with water clear pond, kill bacteria and wild fish. On March 24, 50-70 cm of fresh water was injected. Adjust water quality, apply appropriate amount of organic fertilizer per acre, so that the water to maintain transparency of about 25 cm.
3. Putting on seedlings on April 3rd, stocking males with a rate of 95%, robust, non-injury and disease-free, neatly-sized rainbow trout seedlings, specifications 6-10 cm/tail, stocking density of 2000 tails/mu. On April 8, the seedlings have adapted to the new environment, gradually adding salt water to regulate salinity, increasing their salinity by 5 cents each time, stabilizing them for 3-4 days before continuing to increase salinity into seawater, and finally stabilizing salinity at 15 ‰. Between 20 miles. The entire salinity adjustment process takes 15 to 20 days. The survival rate of rainbow trout seedlings is about 95%.
4. Daily management (1) The feed management feed is expanded tilapia, with a protein content of about 30%, with good stability and palatability. Baiting do "time, positioning, qualitative, quantitative", fed 2 times a day sooner or later, the daily feeding accounted for 3% -8% of body weight of fish, and depending on the water temperature, water quality, food intake and other flexible adjustments. The compound vitamins were added to the feed every 2 weeks at a dose of 2 g/kg feed for 3 to 5 days.
(2) In the process of water-cultivation, basically no water is changed in the early stage, and after the high-temperature period comes in June, the amount of water is gradually increased. Generally, the water is changed every two weeks, and each time the water is changed by 1/4, so that the water in the pond Keep light brown or oil green, transparency 25-35 cm, dissolved oxygen above 3 mg / l, pH 72-82, ammonia nitrogen less than 01 mg / l. Change in salinity within 5 inches of each change of water.
(3) Prevention of disease Maintaining good water quality and reasonable nutrition are the key to reduce the incidence of disease. Use 02- 03 mg/L of chlorine dioxide to splash the whole pond once every 15 to 20 days to disinfect the water body.
Second, the results of dry ponds in late November, a total of 30,930 kilograms of rainbow oysters, the output value of 278,370 yuan, deducting feed costs and other production costs, net profit of 103,250 yuan. During the aquaculture process, photosynthetic bacteria and multivitamins were added to the feed fed from pond No. 2 and the aquaculture effect was significant.
III. Discussion 1. Effect of changes in salinity on rainbow trout The rainbow trout grown in seawater ponds was found to grow faster than freshwater rainbow trout during aquaculture. This may be due to changes in salinity affecting the growth of rainbow trout. During the aquaculture process, the water must be changed at regular intervals (keeping the pool fresh and not aging). This will inevitably cause changes in the salinity of the pool water. Although the rainbow trout is a wide-salinity fish, the salinity changes in the pool water make it necessary for body fluids to penetrate. Pressure regulation, this process rainbow trout growth delay.
During the breeding process, when the amount of water changed in the pond was too large and the salinity change was greater than 9 ,, the appetite decreased significantly in the rainbow trout. This process continued for 2-3 days. By comparing the situation of breeding rainbow trout with three cages in the nearby sea area, it was found that when the salinity of seawater in the sea area is greater than 30‰, the growth of rainbow trout is significantly slowed.
2. The role of adding complex vitamins and photosynthetic bacteria in feeds The addition of complex vitamins and photosynthetic bacteria to feeds will help increase the growth rate and survival rate of rainbow trout. This is because:
(1) Photosynthetic bacteria are rich in bacterial protein, vitamins, growth-promoting and disease-resistant factors, which can enhance the body composition of rainbow lice. In addition, photosynthetic bacteria can also secrete various digestive enzymes in the intestinal tract of rainbow trout and promote rainbow trout to feed. Digestion and absorption, improve feed utilization, and promote growth;
(2) Multivitamins are rich in ingredients that promote and improve the physiology of fish.
3. Diseases in the rainbow arid seawater pond cultivation process, fewer diseases, common diseases are enteritis, fish gills, oblique tuberculosis. The main causes are deterioration of water quality, excessive changes in salinity, and malnutrition. Without long-term water changes, water quality deteriorates, ammonia and nitrogen levels in water increase, eutrophication of water bodies, and large numbers of bacteria and parasites multiply, eventually leading to disease outbreaks. When the salinity changes by more than 10 ,, rainbow trout produces strong stress responses. The decline in body resistance has caused diseases; according to studies conducted by the American Soybean Association, the lack of unsaturated fatty acids (EPA and DHA) in marine culture fish will hinder fish development and weaken the body.
In response to the problems encountered in this breeding process, the author considers improving the Rainbow Bohai Seawater pond culture technology from the following three aspects.
(1) When changing the water, the change of the salinity of the pool water should be minimized, preferably within 3 inches;
(2) It may be considered to breed other economic fish and increase the economic benefits of a unit of water. Mixed economic fish need to avoid overlap in feeding habits and put them in reasonable quantities in order to achieve the best fish load or environmental capacity for a unit of water. The economic fishes that can be considered for polyculture include American redfish, squid, flower-tailed pepper oysters, yellow finned oysters, flower pods, etc.;
(3) Strengthen the nutrient deployment of seawater rainbow trout and formulate a feed for rainbow trout cultivation with balanced nutrition and moderate price, which lays the foundation for the development of rainbow trout seawater scale farming.
Amy Hookah,Zinc Hookah ,Zinc Alloy Hookah
Fenghua Jade Motor Co., Ltd. , http://www.qiuzanhookah.com