Technical points:
1. Water quality control before seedling release:
According to the measurement results of 13 indicators (water temperature, odor, water color, specific gravity, pH, K+, Na+, Ca2+, Mg2+, Cl-, SO42-, carbonate alkalinity and salinity), comprehensive water quality control and management (including biological, chemical and physical aspects) were carried out for different water quality types in the aquaculture area.
2. Water quality control in aquaculture:
The quality of water quality control is the key to the success of aquaculture. Water quality directly affects the survival and growth of cultured organisms. The key to maintain good water quality is to keep the water temperature, salinity, pH value, carbonate alkalinity, nutritional factors and beneficial microorganisms at a reasonable level, so as to avoid the damage of "stress reaction" to organisms and the outbreak of various secondary diseases. Water quality control includes the following aspects:
(1) Reduce turbidity and viscosity of water: control proper transparency, and regularly use water quality improvers and water quality protectants such as zeolite powder to reduce turbidity and viscosity of water and reduce organic oxygen consumption.
(2) Stabilize the water color and maintain a reasonable algal-bacterial system. Regularly put photosynthetic bacteria and other microecological agents in aquaculture water to promote the microecological balance of water. Fertilize irregularly according to water color.
(3) Reasonably replenish water, and pay attention to the storage of aquaculture ponds after early spring according to specific conditions. Fresh water should be supplemented according to conditions and needs after seedling release. Water should be added at about 10 cm every time, and it is advisable to add water once every 10 day to improve water quality and promote the molting of shrimp and the growth of fish.
(4) Scientific feeding, using high-quality and high-priced feed, and reasonable feeding to avoid the accumulation of organic matter caused by inferior feed, which will lead to water pollution in the pond.
(5) Disinfect regularly, and use disinfectant every 7 ~ 10 days in the breeding process to reduce the total number of bacteria in the water. Pay attention to the use of disinfectants and biological agents should be staggered for 5 ~ 7 days to avoid affecting the use effect of biological agents.
(6) Rational use of aerator. Generally, the 4.5 mu semi-intensive cultivation mode must be equipped with a 3 kW aerator, which can be appropriately increased where conditions permit. Only by maintaining a high level of dissolved oxygen (above 5 mg/L) in aquaculture water can the incidence of fish and shrimp be effectively reduced and the growth be promoted.
The use of aerator depends on weather, culture density, water quality conditions and biological activities. The start-up time of intensive culture pond is generally not less than 5 hours a day in the early stage of culture and not less than 18 hours in the late stage of culture. If the weather is abnormal, the start-up time should be extended appropriately.
(7) In ponds with salinity of saline-alkali water above 5, the water quality should be detected in time after adding fresh water, and water quality improvers should be added in time to keep the physical and chemical indexes of aquaculture water within a suitable range.
Normal water quality conditions of ponds: The water depth of ponds should be more than 2.0m, the transparency should be 20-40cm, and the pH value should be 7.5-9.0. For severe saline-alkali water, we should adjust the fresh water source and improve the water quality through artificial deployment technology.
The water depth of the shrimp pond should be above 1.5m, the carbonate alkalinity should be below 5me/L, the transparency should be 30-40cm, the pH value should be 7.8-8.6, and the salinity of the pond water should be1-30g/L. ..