Dead fish under the ice?

I think there are two kinds of dead fish in winter:

The first one is what you call hypoxia.

The second is bacterial infection, illness and death.

Freezing to death is generally not considered, mainly depending on your local weather. Generally speaking, the temperature at the bottom of the pond is about 4 degrees, and the water surface is about 0 degrees. If the water is too shallow, it may cause fish to freeze to death.

Here are some advertisements from which we can get some knowledge. The landlord can refer to the following.

In autumn, the temperature drops gradually, and the fish (shrimp) carried in the pond increases obviously. The water environment in the pond is changed by feeding, fertilization and medication. The climate in autumn is changeable, with more rainy days and less light, which is easy to cause hypoxia and floating head. At the same time, the increase of ammonia nitrogen, nitrite and hydrogen sulfide concentration may also lead to the deterioration of water quality.

(1) The water quality should be determined regularly. Such as pH value, transparency and physical and chemical indexes of dissolved oxygen, such as ammonia nitrogen, nitrite and hydrogen sulfide, keep dissolved oxygen above 5mg/L, pH value 7.5/8.5, transparency at 30/40cm, and indexes such as ammonia nitrogen, nitrite and hydrogen sulfide within a suitable range;

(2) Water injection and water change shall be carried out in time. If the water quality of the source water of the outer river (lake) is good, it can be injected 1 0/5 days, about 20 cm each time; If the water quality of the source water is poor, you can choose sunny weather, and use compound microbial preparations once every 15/20 days, such as "Collier", "Xifeili" or "Eco-treasure". At the same time, we should pay attention to not using disinfectants immediately after using microbial agents, in order to prevent the killing of beneficial bacteria and affect the effect of biological agents on regulating water quality;

(3) Use oxygen-increasing equipment in time, and start the oxygen-increasing machine or water pump at different times according to different weather conditions. Persist in opening at noon on sunny days and not at night; It opens in the early morning on cloudy days and does not open during the day; The floating head used to open, and it opened in the middle of the night on rainy days. At the same time, prepare the first-aid "oxygen-increasing spirit" (the oxygen from Yongtai Chemical is an effective first-aid oxygen-increasing agent) to prevent the occurrence of anoxic floating head and reduce unnecessary losses.

In winter, after the fish species and fish that do not meet the commercial specifications are merged in the pond, the oxygen demand of the fish increases due to the increase of fish density in the pond, and the frozen water surface is closed. At this time, if oxygen is not replenished in time, it will easily lead to the death of fish, and sometimes the loss is serious. Even if the anoxic fish don't die in winter, it will seriously affect the growth in the coming year, leading to a serious reduction in production. Therefore, supplementing oxygen to fish in winter can not only prevent hypoxia death, but also be beneficial to rapid growth in the following spring, thus increasing yield and benefit. However, it is almost impossible to change water in winter. At this time, the piece of oxygen in Yongtai Chemical is a good first choice for increasing oxygen.