The use of plastic greenhouses to heat up and raise large eye larvae to five young crabs is a good way to improve the survival rate and stocking size of crab seedlings. It has the characteristics of less land occupation, small investment, quick effect, easy management, and large profits. My field began to cultivate big eye larvae from 1955 and accumulated some successful experiences. Now the main technical points are introduced as follows:
First, the cultivation pool selection and construction
Juvenile crab breeding ponds should generally be chosen to be sheltered from the wind, quiet, well-watered, and earthen ponds. The size of the pond can be determined according to the scale of cultivation. Generally, 60-1000 square meters is more suitable, the pool is rectangular, the depth is 1-1.5 meters, and the slope is slightly larger than the slope of the aquarium, and the water level is between 0.5-1.0 meters. , Using piles of wood and bamboo and other materials to set up large sheds on the pool, cover the sheds with agricultural film, and compact the four surrounding feet.
Second, seedling stocking
Choose seedlings that have been bred by the crabs in the Yangtse River water system and have been fully diluted in the breeding grounds. The salinity has reached between 3 and 20%. The seeds and seedlings are neat in size, robust in shape, and free of disease and injury. Quickly spread out, between 12 and 160,000 per kilogram. The stocking density per mu is about 400,000.
Third, water quality management
The big eye larvae should fertilize the water quality in the week before entering the pool, increase the plankton content in the water, keep the water temperature above 18°C, the temperature difference should not change more than 2°C in the short term, and the PH value should generally be between 7-8. When the larvae enter the pool, a reasonable amount of fresh water is added. The daily water exchange volume is above l/3, and the time for changing the water is usually selected after noon. Sprinkle lime regularly to improve water quality and increase calcium ion content in the water. Smaller pools of water should be equipped with flushing pumps.
Fourth, reasonable feeding
After the big eye larvae enter the cultivation pond, there must be a certain amount of plankton in the water, and the aquatic plants such as water peanut and water hyacinth cover more than l/3 of the total water surface, and the daily feeding of animal Feed such as egg yolk and small trash fish can be performed. In the first few days, the amount of larvae should be about 200% of the weight of the larvae, feeding once every two hours. After entering the first phase of young crabs, the daily feeding amount will be reduced to 50-80%, and the number of feedings will be 3-4 times. Feeding points should be set on the shallow water area near the water surface or on the grass in the pool, and the water should be evenly fed at multiple points, and the appropriate amount of locust should be added.
V. Disease Prevention
Before entering the pool, big eye larvae must be thoroughly sanitized and often keep the water fresh. They must completely remove the enemy organisms and frogs, water snakes, and water mice. If it is found that malachite is splashed with 0.1ppm of malachite green, it is repeated 3-5 days later. It was found that soft-shell disease increased feeding of fish meal, and parasitosis such as crab slaves and bryozoans was splashed with 0.5ppm copper sulfate solution. For ciliate disease, 30% formalin 5 to 10 ppm Quanchiposa can be used, and if necessary, repeat l-12 times.
First, the cultivation pool selection and construction
Juvenile crab breeding ponds should generally be chosen to be sheltered from the wind, quiet, well-watered, and earthen ponds. The size of the pond can be determined according to the scale of cultivation. Generally, 60-1000 square meters is more suitable, the pool is rectangular, the depth is 1-1.5 meters, and the slope is slightly larger than the slope of the aquarium, and the water level is between 0.5-1.0 meters. , Using piles of wood and bamboo and other materials to set up large sheds on the pool, cover the sheds with agricultural film, and compact the four surrounding feet.
Second, seedling stocking
Choose seedlings that have been bred by the crabs in the Yangtse River water system and have been fully diluted in the breeding grounds. The salinity has reached between 3 and 20%. The seeds and seedlings are neat in size, robust in shape, and free of disease and injury. Quickly spread out, between 12 and 160,000 per kilogram. The stocking density per mu is about 400,000.
Third, water quality management
The big eye larvae should fertilize the water quality in the week before entering the pool, increase the plankton content in the water, keep the water temperature above 18°C, the temperature difference should not change more than 2°C in the short term, and the PH value should generally be between 7-8. When the larvae enter the pool, a reasonable amount of fresh water is added. The daily water exchange volume is above l/3, and the time for changing the water is usually selected after noon. Sprinkle lime regularly to improve water quality and increase calcium ion content in the water. Smaller pools of water should be equipped with flushing pumps.
Fourth, reasonable feeding
After the big eye larvae enter the cultivation pond, there must be a certain amount of plankton in the water, and the aquatic plants such as water peanut and water hyacinth cover more than l/3 of the total water surface, and the daily feeding of animal Feed such as egg yolk and small trash fish can be performed. In the first few days, the amount of larvae should be about 200% of the weight of the larvae, feeding once every two hours. After entering the first phase of young crabs, the daily feeding amount will be reduced to 50-80%, and the number of feedings will be 3-4 times. Feeding points should be set on the shallow water area near the water surface or on the grass in the pool, and the water should be evenly fed at multiple points, and the appropriate amount of locust should be added.
V. Disease Prevention
Before entering the pool, big eye larvae must be thoroughly sanitized and often keep the water fresh. They must completely remove the enemy organisms and frogs, water snakes, and water mice. If it is found that malachite is splashed with 0.1ppm of malachite green, it is repeated 3-5 days later. It was found that soft-shell disease increased feeding of fish meal, and parasitosis such as crab slaves and bryozoans was splashed with 0.5ppm copper sulfate solution. For ciliate disease, 30% formalin 5 to 10 ppm Quanchiposa can be used, and if necessary, repeat l-12 times.
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