Measures for regulating dissolved oxygen in fish ponds by fish culture

Regular injection of fresh water in the case of high-density culture, there are more residual bait and dirt in fish ponds, and anaerobic fermentation produces harmful substances such as ammonia nitrogen and hydrogen sulfide, which worsens the water body, especially in high temperature season, and the water quality deteriorates faster. Therefore, regular water injection is one of the most commonly used and economical methods to regulate water quality. Generally, new water is injected once every 7 to 10 days, with a depth of 15 to 20 centimeters each time. When the deterioration of pool water is relatively serious, water exchange measures should be adopted to maintain good water quality conditions. For ponds with silver carp and bighead carp, the water color should be grass-green or tea-brown, and the transparency should be 20-30 cm deep; for ponds dominated by grass and carp, the water color is lighter than that of silver carp and bighead carp ponds, and new water should be irrigated once every 7-10 days, and the water level should be raised by 15-20 cm each time. Fish ponds should try to keep the highest water level in summer.

Stirring the sediment regularly can promote the continuous decomposition of the sediment and indirectly control the change of water quality. Generally, it is stirred once every 10 to 15 days, and each stirring area is not less than 1 stroke 3 of the water area, and the best stirring effect is at noon on a sunny day, but do not stir in muggy and low pressure weather.

The pond with aerator should be equipped with special aerator, of which impeller type is the best. Turning on aeration can make the water convection, increase the amount of dissolved oxygen in the water and emit toxic gas.

Proper application of chemical fertilizer can make phytoplankton maintain appropriate density and exuberant living condition for fish to eat. At the same time, phytoplankton can absorb nutrients in water and produce oxygen through photosynthesis, thus improving water quality. Fertilization in fish ponds in high temperature season should be based on chemical fertilizer and less organic fertilizer. Generally, in ponds with thin water quality, 2.5 kg urea per mu and 5 kg calcium superphosphate should be applied every 5-7 days. If organic fertilizer is to be applied, it must be fully fermented and a small number of times should be used.

Using drugs to improve some ponds with high density of fish culture and can not often change water, quicklime should be applied regularly to regulate water quality and reduce the toxicity of toxic gases such as hydrogen sulfide. Each mu of pond can use 15 kilograms of quicklime, sprinkle the whole pond after adding water, every 20 days or so. Photosynthetic bacteria have the advantages of purifying water quality and increasing the amount of dissolved oxygen in water. They can also be used as feed for filter-feeding fish and sprinkled in the whole pond every 20 days. There are too many zooplankton in the fish pond, which can be killed with trichlorfon, 0.3 × 0.5 ml per cubic meter of water. Excessive cyanobacteria can be inhibited by copper sulfate, 0.7 ml per cubic meter of water. When floating head occurs in fish, oxygen enhancers and other related drugs can also be selected to increase oxygen.

Transplanting aquatic plants to improve aquatic plants as the primary productivity of water body can control the growth of algae in fish ponds and play a good role in water purification. According to the actual situation of the fish pond, breeders can reasonably introduce aquatic plants such as verticillium verticillata, Houttuynia cordata, water hyacinth and duckweed into the water according to local conditions and scientific planning, so as to adjust the water quality and improve the level of dissolved oxygen.

Capturing aquatic animals to regulate and control aquatic animals is the "consumer" in the water body. Proper aquaculture can promote the balance of water ecosystem and regulate water quality. For example, capturing carp and crucian carp can make full use of the residual organic matter in the water, greatly reduce the decay and decomposition of organic matter at the bottom of the water, and reduce the probability of pollution; interculture herring can restrain the consumption of nutrients and oxygen by snails and other organisms in water; silver carp can make full use of plankton and other natural bait resources in water to control water fatness; bighead carp can restrain rotifer in water. Interculture of grass, mackerel and mackerel can ensure sufficient dissolved oxygen in water and purify the culture environment, while mandarin fish, snakehead and sea bass can effectively control the growth and reproduction of wild fish and shrimp in water and reduce the competitive pressure of food and oxygen with the main fish culture.