Water quality is required to be fresh in intensive ponds, but it is not as transparent as possible. Water transparency is a manifestation of water body fatness. The greater the transparency, the thinner the water body and the less phytoplankton in the water, the weaker the photosynthesis. The vast majority of dissolved oxygen in ponds comes from photosynthesis of phytoplankton. When the transparency is high, the amount of oxygen produced by photosynthesis will be reduced, and the state of hypoxia or hypoxia will often occur, affecting the productivity of aquatic products. Generally, the transparency of aquaculture ponds is 20-40 cm, and if more than 40 cm, fertilizers should be properly applied to make the water body have a certain amount of phytoplankton, so as to maintain the intensity of photosynthesis and oxygenation.
Aerators are one of the necessary equipment for pond intensive care. Some farmers believe that oxygen aerators are used for anoxic emergency, and generally do not open or based on experience only in the evening and later in the breeding period. In fact, the role of aerators in addition to oxygen, there are stirring water, aeration effect. If you wait until you are anoxic, it will be too late and it will greatly affect the growth of the fish. In addition, the oxygenating effect of aerators is limited, and their oxygenation capability is far less than that of photosynthesis and wind aeration. Therefore, aquaculture should also make full use of the other two roles to indirectly improve the state of dissolved oxygen in the water.
The phenomenon of oxygen jump in the pond over 2 meters is very obvious. At this time, opening a 1.5-kilowatt impeller aerator for 1 hour can make the oxygen in the upper and lower layers of the 3-mu pond water even, so that the entire water body can maintain a high level of dissolved oxygen. , which can greatly shorten the time to open the aerator at night. In the process of rotating the aerator, the toxic substances at the bottom can be poured out to the surface of the water body and oxidized and decomposed in the high dissolved oxygen zone of the surface layer or escaped in the form of gas, thereby reducing the organic oxygen demand of the bottom layer. Reduces the risk of hypoxia. In addition, the photosynthetic activity of phytoplankton is not strong during overcast and rainy days, and the strength of oxygenation in the water body is weakened, while the oxygen-consuming factor is relatively increased, and oxygen deficiency is prone to occur. At this point should fully play the role of aerator, early opening, improve dissolved oxygen status, prevent floating head.
In general, the cultivation of fingerlings is one of the measures to increase the yield of ponds, but the stocking density is not as large as possible. There is a reasonable range of pond water aquaculture capacity for various models, beyond this range will not receive the expected results. If the density is too large, although the yield may be increased, the size of the developed fish is relatively small, which is not economical. The increase in density will inevitably increase the amount of feed and increase the feed coefficient. Excessive excretion can also deteriorate the water quality of the pond, causing anoxic and fish disease outbreaks.
Regular disinfection is one of the effective measures to prevent fish diseases, but not the shorter the disinfection cycle, the better the efficacy. There are a large number of beneficial microorganisms in the pond water environment and inside the fish body. They can degrade and transform contaminants in the water body, and their antagonism can also inhibit and kill harmful microorganisms. Pathogenic microorganisms are often found in bodies of water and fish, and their role in a good water environment is inhibited. When the environment deteriorates and the balance is out of balance, they will work and cause an outbreak of fish diseases.
The protein content of feed is one of the criteria for measuring the level of feed nutrition, but not the higher the protein content, the higher the feed quality. In essence, fish and shrimp do not need protein but amino acids. However, animals cannot synthesize amino acids from simple inorganic substances, and they must obtain amino acids directly or indirectly from the uptake of animal and vegetable diets. Therefore, fish and shrimp feed must not only pay attention to the amount of protein, but also pay attention to its quality.