Summer is the season when crabs and shrimps grow, but also when the weather changes and water quality changes, it is easy to have an outbreak. How to improve the safety of crabs and shrimps in the summer is recommended.
First, adjust the water quality
The transparency of the crab and shrimp mixed ponds is controlled between 50 and 60 centimeters, the pH is between 7 and 8, the dissolved oxygen is more than 4 milligrams per liter, and the nitrite is less than 0.02 milligrams per liter. The specific water quality regulation mainly adopts the following measures.
1. Changing the water: In the summer, the number of water changes, the time, and the amount of water exchange are mainly based on water quality and weather conditions. Usually, the water is changed every 7 to 10 days. Each time the water is changed by about 20%.
2. Lime and superphosphate: 10 to 15 days in summer. Use quick lime, 10 to 15 grams per cubic meter. After using lime for 3 to 4 days, use superphosphate at 2 to 2.5 kilograms per acre. The application of 1 or 2 times can prevent the lack of phosphorus in the pool water and promote the growth of river crabs and shrimps.
3. Regular use of biological agents: Regular use of biological agents (such as EM bacteria, super-concentrated composite bacillus) in the summer to regulate water quality, combined with internal use, can avoid the use of disinfectants on the damage of the shrimp. General use of EM bacteria once every 10 to 15 days, each 1 meter deep per acre 250 grams. After heavy rain or windy weather, the water body is thick and the transparency is reduced. The super-concentrated composite bacillus can be used to promote the sinking of suspended matter, decompose organic matter in the bottom layer of the pool, improve the transparency of the pool water, and improve water quality and sediment quality.
4. Turn on aerators in a timely manner: Green shrimp requires high dissolved oxygen, and crabs also prefer fresh water and high dissolved oxygen in water, so they must be equipped with aerators. The principle of opening an aerator is: open at noon on a sunny day, open early in the morning on cloudy days, open in the middle of a rainy night, open late in the evening, open early in the floating head, open more and more, have less wind, open at high temperatures, and open at low temperatures.
Second, control the area of ​​aquatic plants
In summer, the light intensity is strong and the aquatic plants grow vigorously. If the area covered is too large, the water quality will be damaged, resulting in lack of oxygen in the pool water. It is advisable to cut away the excess plants and control the area of ​​the aquatic plants to 40 to 50% of the pond area.
Third, reasonable feeding
Green shrimp is mainly based on compound feeds. It focuses on mashing up some small-sized trash fish during the shell stage, and the feeding time of the shrimp. Every day from 7 to 8 am, and from 5 to 6 pm in the morning, 30% of the daily feed is put in the morning. At 70% in the afternoon, the bait should be thrown evenly in the deeper water area around the pool in the morning and in the shallow water area in the afternoon.
Fourth, timely reduction of shrimp density
In the ponds where the main crabs are raised, the shrimps are mixed. The shrimps that grow by the egg-bearing shrimps can reach more than 3 cm. According to the density of the shrimps, the cages or hand-dipping nets can be used to catch the large-size shrimps and adjust the shrimps' density. , reduce the total biomass in the pool.
V. Cleaning up wild fish
Trash fish compete with the crabs and shrimps to fight for oxygen in the pool. To reduce production costs and increase crab and shrimp specifications, it is necessary to control and clean the wild fish. Usually the pond water is filtered with a 60 mesh screen.
Sixth, disease prevention measures
1. In July and August, according to the pond water quality, weather, etc., to avoid the use of insecticides at the peak of crab and shrimp clams.
2. In continuous rainy weather, pay attention to prevent disease, available Quanchiposa and internal use.
3. In the middle and late August, shrimp and crab enteritis should be prevented. Garlic seeds (garlic seed smashed, do not cook) should be mixed with baits once a day for 3 days.
4. Disinfectants, such as dibromohydantoin, can be used for other bacterial and viral diseases.
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