What are the treatment methods for oxygen depletion in fish ponds in winter?

In winter, fish activity decreases. Although their oxygen demand is not high, because the fish pond freezes over, the water surface cannot directly dissolve oxygen from the air. In addition, aquatic plants such as waterweeds in the water body produce less oxygen due to lower temperatures and weakened photosynthesis, which easily causes oxygen depletion in the water. What should be done about oxygen depletion in fish ponds in winter? How should it be treated?

1. Clear away snow

During the freezing period in winter, if snowy weather occurs, promptly clear away the snow on the ice surface of the fish pond so that sunlight can shine into the pond water and ensure that photosynthesis by the green plants in the water proceeds normally.

2. Break the ice to add oxygen

After the water surface is sealed by ice, break open the ice every morning and evening. Generally, for each mu of fish pond, ice openings of 5-6 sq m should be broken open. At the same time, remove the broken ice pieces to prevent them from quickly freezing again.

3. Add and change new water

During the period when fish overwinter, in addition to maintaining the highest water level to increase oxygen and keep warmth, new water should also be regularly added to improve the fish's living environment and increase dissolved oxygen. Generally, water should be added once every 15 to 20 days. If the pond water quality deteriorates and shows signs of aging, the old water and harmful substances in the pond should be promptly discharged. Each water change should be 1/3 of the original pond water, and then new water should be promptly added. Another reason for oxygen depletion in ponds in winter is that the water quality was not properly handled in autumn. The pond bottom should be treated before feeding is stopped, because every day a large amount of fish feed is put into the pond to feed the fish, and a large amount of fish feces is discharged into the pond, causing high organic matter content at the pond bottom. The first major problem with high organic matter is oxygen consumption. The second problem is that rotifers like environments with high organic matter. At this time, human intervention should be used to reduce the organic matter content.

4. Apply fertilizer appropriately

When the fish pond water is clear and lean, a certain amount of inorganic fertilizer can be applied at noon on a sunny day. In this way, it can both promote the growth of phytoplankton in the water and keep it warm, and also increase dissolved oxygen in the water through photosynthesis. The fertilizer must contain both nitrogen and phosphorus.

5. Regularly stir the pond

The purpose is to turn over the bottom mud, mix the upper and lower water bodies, promote the rapid decomposition of harmful substances at the pond bottom, and at the same time ensure that the fish do not suffer from oxygen depletion during the overwintering period. The method is to use a bamboo pole to stir part of the pond bottom at noon on a sunny day, and after some time stir another part of the pond bottom.

6. Splash chemical agents

Regularly apply appropriate amounts of quicklime, bleaching powder and other chemical agents to the pond to increase dissolved oxygen in the fish pond and improve water quality. One of the reasons for low dissolved oxygen in the water body of fish ponds in winter is that there are few algae in the water body and rotifers appear. Rotifers consume a very large amount of oxygen. When rotifers and algae are out of balance and the algae have all been eaten by rotifers, photosynthesis is low, very few oxygen-producing algae remain, transparency increases, and the water color is pale. If human intervention is not used during this period, great losses will result, such as fish in winter crowding the edges with bleeding on the body surface, frequently swimming in the upper layer, and severe frostbite of the fish body due to the low water temperature in the upper layer (fish death from oxygen depletion).