In recent years, a number of aquaculture areas in China’s aquaculture fish, such as grass carp, crucian carp, spotted fork-tail catfish, catfish, yellow catfish, etc., in the early spring after the winter outbreak of mass mortality phenomenon, the symptoms are mostly manifested as the body surface hemorrhage, ulceration, accompanied by secondary water mold disease. After autopsy, it can be found that the liver and gallbladder of the sick fish are severely damaged, and the intestinal wall is thin and hemorrhagic.
Because the disease has not yet been identified pathogen, and the course of the disease is long, difficult to deal with, multi-factors synergistically induced, so it is known as the “overwintering syndrome”, and in some areas is also known as “fish plague”.
Causes of overwintering syndrome
1. Feeding problems: with the lowering of water temperature, some farmers start feeding low-quality feed, or even stop feeding, resulting in insufficient accumulation of fish nutrients during the overwintering, and weakening of body quality.
2. Management problems: excessive breeding density leads to deterioration of water quality and lack of oxygen, non-standard operation of pond transfer, unscientific disinfection and so on.
3. Drug abuse: the abuse of antibiotics, antidotes and other drugs during the breeding cycle, resulting in the strengthening of bacterial resistance in the water, superimposed on the decline in fish immunity is more likely to contract diseases.
Among the above reasons, the feeding problem is particularly prominent.
Common feeding mistakes in before and during overwintering
There are several misconceptions about feeding before and during the overwintering. One of them is that the low temperature in winter reduces the mobility of fish, so there is no need to feed. The second is that the feed price is high, and it is not cost-effective to feed the fish in winter because of the slow growth of the fish.
In fact, if the fish do not have a good nutritional reserve before overwintering, in the long period of overwintering does not get the energy supplementation required for normal growth, it can only consume the nutrients accumulated in the body to maintain life. In the coming year, the fish will lose fat and become weaker, and diseases will be more likely to attack the fish.
The year 2023 is quite difficult for the aquaculture industry. High prices of bulk raw materials, frequent feed price increases, coupled with the downturn in the market for aquatic products, some farmers in order to reduce losses and even before the overwintering has begun to stop feeding, switching to feed wheatgrass, pumpkin and so on. Do not know the more so, after the spring “wintering syndrome” more difficult to control.
In this regard, farmers must be clear-eyed, clear feed inputs and disease, the economic accounts of dead fish, rather than stopping the material to reduce costs, do a good job of “wintering life” is a good recipe.