Because of the small body of water, high stocking density, high temperature, and rapid water pollution, industrialized rearing crickets lack the conditions for self-defense and protection in the natural environment, and are prone to disease and other injuries, resulting in losses. Through experiments, we have found that culturing plankton in Dianchi Lake can control the water quality and form an aquaculture environment where cocoon and plankton coexist and benefit each other. Not only does cockroach grow fast and has a high survival rate, but also it can significantly reduce costs and increase production and achieve stable economic benefits. . The results of the study are reported below:
First, experimental materials and methods
(I) Laboratory pool and feeding management
1. Experimental conditions
The experimental site is the factory-facilitated breeding pond in Changsha Fisheries Technology Promotion Station (25m2/port). The size, shape, structure, experimental conditions and management methods of the two pools are the same. They are smooth cement structures, and the bottom of the pool and the walls are all insulated. During the experiment, the boilers provide heat, and the water temperature is maintained at 30°C (±0.5°C) for a long time. Room temperature 31°C (±0.5°C). The deepest pool water is 0.8M, and 2/3 of the pool floor is covered with 10CM thick sand. Water is pumped from the pond into the preheating pool and then warmed into the dike pond. Drainage is naturally discharged at the bottom of the pool. The greenhouse is completely closed. Every day, exhaust fans are vented outdoors using air exhaust fans and inflated with water pumps. Because there is no natural light, two 250w far-infrared lamps are used for lighting such as feeding and sewage disposal.
2. Restocking and management
Two pools of experimental pools (No. 2 pool) and control ponds (l ponds) were placed at the same time on November 7, 1996, about 5 grams of juvenile fish, including: 604 ponds No. 2, and 712 ponds No. 1. The No. 2 pool adopts phytoplankton which takes cryptophyte as the main body to control the water quality of the Dianchi Lake. Generally, it does not change the water, but only inflates. According to the situation of the sewage in the rearing period, 7 to 10 days, a small amount of water is discharged from the bottom valve, but the water is discharged once. Do not exceed 1/4 of the total amount of pool water, strictly control the PH value and water temperature of the pool water, and try to maintain stable environmental conditions for the growth of cryptophytes in the pool water. L No. 1 pool is under normal factory aquaculture management. At least two cuts of water are taken at the end of each week and the water is often cleaned. The other two ponds had the same management of other feeds, and they were fed twice a day. Domestically grown juveniles were used for feeding and supplemented with vitamins and disease prevention drugs. Every day, a person manually checks gas, water temperature, and other observation data, and removes bait and residual bait, and finds that there is an abnormal situation in time to deal with it, so as to ensure the normal growth of hernia.
(II) Observation methods
1. Plankton qualitative and quantitative observations from January 1996 to the end of May 1997 were taken at regular intervals from the 1st and 2nd pool water samples respectively to detect the type, amount, and change of plankton, specific detection and conversion methods according to "Terrestrial Fisheries Natural Resources Survey Trial Practice". In order to obtain data on the day-night changes of plankton in a fully-sealed greenhouse, a 48-hour continuous pool bottom and surface sampling test was conducted in January.
2. Determination of water chemistry index
At the same time as the sampling and detection of plankton, the transparency, dissolved oxygen, oxygen consumption of organic matter, and ammonia nitrogen content of the pool water samples were tested. The collection and testing methods were all tested on the spot according to the “Freshwater Aquaculture Chemistry†method.
3. Dianchi water containing bacteria number culture test
In January and September, the water quality of the l and 2 ponds and the growth of earthworms were stable (at least one week without pesticide application and water exchange). Each of the water samples was diluted and inoculated on a C. scutellaria medium plate and placed at a constant temperature incubator at 31°C. Hours and 48 hours later, the test statistics contained the number of bacteria and mold. And compared with outdoor ponds.
Second, the experimental results
(i) Growth rate and yield of alfalfa
From the larvae to the lower pool, randomly check 10 larvae at the 1st and 2nd pools every 15 days (Table 1:1 ponds, 2 pond larvae weight check table). On May 5, 1997, an expert from Changsha Science and Technology Commission organized the acceptance of the No. 1 and No. 2 pools. After six months of cultivation, the Ganchi test results showed that there were 572 ponds out of No. 2 pool with a net weight of 123.3 kg. Weighing only 212g, the output per square metre is 4.85kg; in No. 1 pond, there are 672, and the net weight is 93.8kg, and the average weight is 1398 per square meter, and the yield per square meter is 3.75k8. On the 2nd she has a higher yield than the No. 1 pond. At 3%, individual growth rates were 52% faster. Net income of 250 yuan per square meter, significant economic benefits.
(b) Plankton observations
Although the ponds No. 1 and No. 2 were water sources for the same pond and the water temperature and air temperature were the same, the changes in plankton in ponds No. 2 and No. 1 were still different from the observations of regular sampling and continuous sampling. The type of phytoplankton in pond No. 2 was The predominance of Cryptophyta is more obvious. In the l and February, where the change of pool water is relatively stable, the predominance of cryptophytes is more obvious and stable, and there is more species of phytoplankton in the No. 1 pond water, and there are no dominant populations, mainly in green algae. The phytoplankton species in the outdoor pond water were more consistent with those in the same period (Table 2: Comparison of species and amounts of phytoplankton in the No. 2 and No. 2 pools).
(III) Water Chemistry Test Results
The results of chemical tests on pools 1 and 2 showed that although pond 2 consumed 38.7% more feed than pond 1, pool water was greyish black for a long time and rarely changed water, but pool 2 was significantly better than pond 1 (Table 3: Monthly list of water-soluble oxygen, ammonia-nitrogen content, oxygen consumption of organic matter in the No. 1 and No. 2 pools). The total dissolved oxygen was 9.7% higher than that of No. 1 pond, while the organic oxygen demand and ammonia nitrogen content were 10.6% and 12.99% lower respectively.
(d) Dianchi water quality bacterial test results
Dilutions of ponds 1 and 2 and outdoor inflow ponds were diluted 10 (4) to 10 (8) times inoculated on a Catch's medium plate and incubated at a constant temperature of 31°C.
First, experimental materials and methods
(I) Laboratory pool and feeding management
1. Experimental conditions
The experimental site is the factory-facilitated breeding pond in Changsha Fisheries Technology Promotion Station (25m2/port). The size, shape, structure, experimental conditions and management methods of the two pools are the same. They are smooth cement structures, and the bottom of the pool and the walls are all insulated. During the experiment, the boilers provide heat, and the water temperature is maintained at 30°C (±0.5°C) for a long time. Room temperature 31°C (±0.5°C). The deepest pool water is 0.8M, and 2/3 of the pool floor is covered with 10CM thick sand. Water is pumped from the pond into the preheating pool and then warmed into the dike pond. Drainage is naturally discharged at the bottom of the pool. The greenhouse is completely closed. Every day, exhaust fans are vented outdoors using air exhaust fans and inflated with water pumps. Because there is no natural light, two 250w far-infrared lamps are used for lighting such as feeding and sewage disposal.
2. Restocking and management
Two pools of experimental pools (No. 2 pool) and control ponds (l ponds) were placed at the same time on November 7, 1996, about 5 grams of juvenile fish, including: 604 ponds No. 2, and 712 ponds No. 1. The No. 2 pool adopts phytoplankton which takes cryptophyte as the main body to control the water quality of the Dianchi Lake. Generally, it does not change the water, but only inflates. According to the situation of the sewage in the rearing period, 7 to 10 days, a small amount of water is discharged from the bottom valve, but the water is discharged once. Do not exceed 1/4 of the total amount of pool water, strictly control the PH value and water temperature of the pool water, and try to maintain stable environmental conditions for the growth of cryptophytes in the pool water. L No. 1 pool is under normal factory aquaculture management. At least two cuts of water are taken at the end of each week and the water is often cleaned. The other two ponds had the same management of other feeds, and they were fed twice a day. Domestically grown juveniles were used for feeding and supplemented with vitamins and disease prevention drugs. Every day, a person manually checks gas, water temperature, and other observation data, and removes bait and residual bait, and finds that there is an abnormal situation in time to deal with it, so as to ensure the normal growth of hernia.
(II) Observation methods
1. Plankton qualitative and quantitative observations from January 1996 to the end of May 1997 were taken at regular intervals from the 1st and 2nd pool water samples respectively to detect the type, amount, and change of plankton, specific detection and conversion methods according to "Terrestrial Fisheries Natural Resources Survey Trial Practice". In order to obtain data on the day-night changes of plankton in a fully-sealed greenhouse, a 48-hour continuous pool bottom and surface sampling test was conducted in January.
2. Determination of water chemistry index
At the same time as the sampling and detection of plankton, the transparency, dissolved oxygen, oxygen consumption of organic matter, and ammonia nitrogen content of the pool water samples were tested. The collection and testing methods were all tested on the spot according to the “Freshwater Aquaculture Chemistry†method.
3. Dianchi water containing bacteria number culture test
In January and September, the water quality of the l and 2 ponds and the growth of earthworms were stable (at least one week without pesticide application and water exchange). Each of the water samples was diluted and inoculated on a C. scutellaria medium plate and placed at a constant temperature incubator at 31°C. Hours and 48 hours later, the test statistics contained the number of bacteria and mold. And compared with outdoor ponds.
Second, the experimental results
(i) Growth rate and yield of alfalfa
From the larvae to the lower pool, randomly check 10 larvae at the 1st and 2nd pools every 15 days (Table 1:1 ponds, 2 pond larvae weight check table). On May 5, 1997, an expert from Changsha Science and Technology Commission organized the acceptance of the No. 1 and No. 2 pools. After six months of cultivation, the Ganchi test results showed that there were 572 ponds out of No. 2 pool with a net weight of 123.3 kg. Weighing only 212g, the output per square metre is 4.85kg; in No. 1 pond, there are 672, and the net weight is 93.8kg, and the average weight is 1398 per square meter, and the yield per square meter is 3.75k8. On the 2nd she has a higher yield than the No. 1 pond. At 3%, individual growth rates were 52% faster. Net income of 250 yuan per square meter, significant economic benefits.
(b) Plankton observations
Although the ponds No. 1 and No. 2 were water sources for the same pond and the water temperature and air temperature were the same, the changes in plankton in ponds No. 2 and No. 1 were still different from the observations of regular sampling and continuous sampling. The type of phytoplankton in pond No. 2 was The predominance of Cryptophyta is more obvious. In the l and February, where the change of pool water is relatively stable, the predominance of cryptophytes is more obvious and stable, and there is more species of phytoplankton in the No. 1 pond water, and there are no dominant populations, mainly in green algae. The phytoplankton species in the outdoor pond water were more consistent with those in the same period (Table 2: Comparison of species and amounts of phytoplankton in the No. 2 and No. 2 pools).
(III) Water Chemistry Test Results
The results of chemical tests on pools 1 and 2 showed that although pond 2 consumed 38.7% more feed than pond 1, pool water was greyish black for a long time and rarely changed water, but pool 2 was significantly better than pond 1 (Table 3: Monthly list of water-soluble oxygen, ammonia-nitrogen content, oxygen consumption of organic matter in the No. 1 and No. 2 pools). The total dissolved oxygen was 9.7% higher than that of No. 1 pond, while the organic oxygen demand and ammonia nitrogen content were 10.6% and 12.99% lower respectively.
(d) Dianchi water quality bacterial test results
Dilutions of ponds 1 and 2 and outdoor inflow ponds were diluted 10 (4) to 10 (8) times inoculated on a Catch's medium plate and incubated at a constant temperature of 31°C.
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