CATDOLL : CATDOLL: What are the requirements for water quality management in pond shrimp farming?

1. What are the requirements for water quality management in pond shrimp farming?

Strengthening the management of shrimp pond water quality and creating a good ecological environment are important measures to achieve high yields of shrimp farming in ponds. Specifically, the following four aspects should be mastered:

(1) Manage the water quality of shrimp ponds in accordance with the requirements of water environment conditions for the growth and development of freshwater shrimps. Freshwater shrimps are crustaceans, and require the dissolved oxygen in the pond water to be above 5 mg/L, the pH to be 7-8, the water transparency to be around 40 cm, the silt at the bottom of the pond to be around 10 cm, the organic matter content to be low, and the water quality to be fresh and lively. During the shrimp farming process, strengthen the monitoring and regulation of water quality, maintain good water quality, and promote the growth of freshwater shrimps.

(2) Manage the water quality of shrimp ponds according to the changing rules of the main water quality factors. Dissolved oxygen is an important factor in water quality. The main sources of dissolved oxygen in water are: first, photosynthesis of green plants; second, wind diffusion, dissolving oxygen leaking from the air into the water; third, artificial measures to supplement oxygen in the water. The consumption of dissolved oxygen in water is: first, oxygen consumption by aquatic organisms; second, wind diffusion, which returns dissolved oxygen in the water to the air; third, oxygen consumption by the decomposition of organic matter in the pond. The diurnal variation of dissolved oxygen in water is: in clear weather, due to the photosynthesis of green plants, a large amount of oxygen is released, and the dissolved oxygen in the water reaches saturation around noon. At night, the photosynthesis of green plants stops, aquatic organisms consume a lot of oxygen by breathing, and organic matter decomposes and consumes oxygen. The dissolved oxygen in the shrimp pond is at its lowest level before dawn. Therefore, it is easy to cause hypoxia in shrimp at night and early morning. In addition, the water quality of shrimp ponds can also cause hypoxia due to irregular fertilization, the death of a large number of algae, or continuous rainy weather. Pond inspections should be strengthened, attention should be paid to changes in water quality and dissolved oxygen, and oxygenation measures should be taken in time to avoid hypoxia accidents and losses. The pH change of shrimp ponds is mainly caused by the metabolites of anaerobic bacteria and the organic acids produced by the decay of leftover bait. In addition, factors such as acid rain can also cause changes in the pH of pond water. The transparency of shrimp pond water is mainly determined by the amount of suspended matter in the water, especially the amount of algae. Usually tea brown and oily green are better, and the transparency is about 40 cm. Water quality management should be strengthened according to the day and night changes of these factors.

(3) Manage the shrimp pond according to the seasonal changes in fishing seasons. In the early stage of stocking shrimp fry, the water depth of the shrimp pond can be kept at about 0.8 meters. August to September is both a hot weather and the peak season for the growth of freshwater shrimp, so the pond water should be filled to a depth of 1.2 to 1.5 meters. The water quality is very easy to change in autumn. Depending on the water quality of the shrimp pond, water should be added or changed once every 7 to 10 days. The amount of water changed should not be too large, generally about 1/4. Or start the aerator regularly to add oxygen to the shrimp pond. In normal times, if the water quality is found to be too rich or too concentrated, water should be added or changed in time to regulate the water quality.

(4) Manage the water quality of the shrimp pond according to weather changes. Keep listening to weather forecasts and patrol the pond in the morning and evening to observe changes in the water quality of the shrimp pond. Take appropriate measures based on the weather, water quality and shrimp activity to maintain good water quality.

This article is from: China Agriculture Press "Green Development and Green Plant Protection"

2. How do aquaculture farmers understand water color and water quality?

The water color of fish ponds can be good or bad. Generally, experienced fishermen judge and adjust the water quality based on the water color of fish ponds. Generally, tea-brown or mung bean-colored water is good water, indicating that there are many types of phytoplankton in the water, especially algae that fish like to eat and are easy to digest, and there are also many zooplankton. In this water color, there are abundant fish bait organisms, indicating that the water quality is good. The water color in the pond is light and clear to the bottom, indicating that there are few plankton in the water. It is thin water, and fertilization and feeding should be increased to improve the water quality. The water color in the pond is dark green or blue-green, mainly due to the excessive reproduction of plankton, especially some blue-green algae that are not easily used by fish. This water is commonly known as "old water". Due to the large amount of biomass in the water, respiration at night will consume a lot of oxygen in the water, causing fish to float in the early morning due to lack of oxygen. Generally, flushing should be done once a week to improve water quality. If new water is not added, the water color will turn reddish brown, brown or even black. This is a sign of deteriorating water quality. It is also the peak time for zooplankton. Large numbers of water fleas can be seen with the naked eye. If new water is not immediately injected, flooding will easily occur, causing large numbers of fish to die. Pay special attention to this situation in summer and autumn, and frequently add new water to adjust the water quality to improve the living environment of fish. Water quality regulation is a link that must be mastered in breeding management. It is necessary to properly feed and fertilize, and to properly inject new water, and often keep the water "fat, fresh, and alive" so that there is sufficient oxygen and abundant plankton in the water, which promotes the fish's appetite and rapid growth.

3. What kind of water quality is needed to raise ornamental shrimp (especially cherry shrimp)? And how to test and maintain the water quality?

The pH value should be stable

4. How to identify the quality of aquaculture water?

The water color reflected by the different types and quantities of plankton is also varied. 1. Better water quality: yellow-brown, oily green, grass green with yellow, dark green, etc. These water colors contain rich plankton and are easily digested by fish. 2. Poor water quality: light green, dark green, blue-green, gray. The plankton contained in these waters are all difficult to digest. The composition of plankton should be changed by adding new water and applying quicklime. Second, look at the oil film in the leeward area. Generally, there is a dark green or smoky gray oil film in the leeward area of ​​the fat pond, which is sticky and foamy. There is less in the morning and more in the afternoon. If there is only a small amount of oil film, the water quality should be ideal, but too much oil film will affect the exchange of gas in the water and gas in the air, and new water should be added to solve it. Third, see if the water color changes. The ideal water quality often changes with different light and time. This is a manifestation of phytoplankton in the vigorous reproduction period. Generally, the water color is light in the upwind direction and dark in the downwind direction. The water color is light in the morning and dark in the afternoon. Fourth, check whether the water has a strange smell. If the phytoplankton in the pond water is not used by fish, it will age and die. If more phytoplankton dies, you will smell a fishy or foul odor from the water in the downwind area of ​​the pond. At this time, you should pay attention to the lack of oxygen and deterioration of the water quality.

5. Why do the shrimps swim toward the sky after being fed?

Freshwater shrimps have a relatively high requirement for dissolved oxygen in water. Usually, the dissolved oxygen is required to be above 5 mg/L. If it is lower than 2.5 mg/L, freshwater shrimps will stop eating; when it drops to 1 mg/L, freshwater shrimps will float to the surface and die due to lack of oxygen. Therefore, ponds for breeding freshwater shrimps should maintain fresh water quality to ensure a good dissolved oxygen environment.

Waterweed is a very important aquatic environment for shrimp farming. Shrimp have a relatively weak swimming ability and can only swim a short distance. They usually climb and crawl on the bottom of the water, on waterweed and other attachments. Waterweed is the main attachment for shrimp to live and move. It plays an important role in three-dimensional utilization and uniform distribution, and is an important basic condition for increasing the density of shrimp stocking. Waterweed is also a hidden place for shrimp to molt, which is conducive to escaping from the invasion of enemies; it can also play a role in avoiding light, shading and cooling in high temperature seasons. The stems, leaves and roots of waterweed are natural green feed for shrimp. Waterweed provides good ecological conditions for the life and growth of shrimp.

Experiments have shown that the feeding intensity of green shrimp is significantly higher at night than during the day. The highest level is after 8 pm, followed by after 8 am. Green shrimp generally digest food in 8-12 hours, so the breeding pond is usually fed twice a day, at 8-9 am and 6-7 pm. 1/3 of the total amount is fed in the morning, and 2/3 of the total amount is fed in the evening. The shallows for feeding in the morning are slightly deeper than those at night.

In places where there are fresh animal bait sources such as small fish, snails, shellfish, etc., it is better to feed them at night.