Hydromycosis, also known as skin mildew, is a common fungal disease in fish. The main symptoms include: the appearance of cotton wool-like white or gray-white visible hyphae in the affected area, increased mucus on the body surface of the diseased fish, loss of appetite, gradual emaciation of the fish, and in severe cases, the fish body is scorched and yellow, and the fish is dead. Water mildew disease not only affects the growth of fish, but can lead to mass mortality in severe cases.
Causes of water mold outbreaks:
The deterioration of water quality can provide a suitable environment for the growth and reproduction of water mold pathogens. Such as:If the water quality is polluted, eutrophicated or not replaced for a long time, the incidence of water mildew will increase accordingly.
There are two periods to pay special attention to:One is the period of low temperature weather in winter: Especially in South China, the reproduction rate of water mold pathogens has slowed down due to the decrease in water temperature, but there are still a certain number of survival and reproduction. When the water temperature drops further, the resistance of the fish also decreases, and the incidence and infection rate of water mold disease will increase significantly. The other is the early spring ice meltIn the northern region, the water temperature gradually increases in spring, but the water quality deteriorates during the ice melt period, which provides a suitable environment for the growth and reproduction of water mold pathogens. In addition, the metabolic activity of fish in spring is enhanced, but the nutrients stored in the body are gradually reduced, resulting in a decrease in resistance and susceptibility to water mold.
In addition,Fish injuries are also one of the main causes of water mold infection。In the process of fishing, transportation, stocking and other operations, if the improper operation leads to damage to the fish body, it will increase the chance of infection with water mold. For example, in the case of California perch pulling nets in winter, raw fish wintering, fertilized eggs hatching, and northern spotted catfish moving to ponds, the possibility of water mold outbreaks is very high.
The main factors leading to water mold outbreaks:
Water temperature is an important factor affecting the occurrence of water mildew。In the low temperature environment, the reproduction rate of water mold pathogens slows down and the incidence decreases. However, with the increase of water temperature, the reproduction rate of water mold pathogens accelerates, and the incidence rate will increase accordingly. In the two periods mentioned above, the temperature suitable for the reproduction of pathogens is 10-15, and the bacteria will be inhibited when the temperature reaches 28.
pH value is also one of the important factors affecting the occurrence of water mold。In water bodies that are too acidic or alkaline, fish are less resistant and more susceptible to water mold. When the pH of the water body reaches 7At 2 o'clock, it is the most suitable for the growth of water mold spores, and the reproduction is the most vigorous. And at a pH of 60 vs. 80, bacteria are generally formed, but the ability to form spores is weak. When the pH reaches 45 vs. 55. At 5, the growth of water mold can be completely inhibited.
In addition,The salinity of the water also affects the occurrence of water mold。In water bodies with high salinity, fish are less resistant and susceptible to water mold. Therefore, in the process of aquaculture, the salinity of the water body should be reasonably controlled, and the salinity should be too high or too low for a long time.
Measures to control water mildew:
Prevention of water mildew begins with frostbite prevention. The degree of frostbite determines the intensity and difficulty of water mold infection, so measures should be taken to slow down the damage of temperature to fish, such as building sheds, heating, changing the bottom, reducing feeding, and deepening the water level before cooling. How to improve the survival rate of overwintering culture. The coldest air has arrived, how to manage the pond?In case of inclement weather,Strengthen water quality management and improve fish resistanceto reduce the area and extent of frostbite, thereby reducing the extent and breadth of water mold outbreaks. In the case of rapid freezing, potassium persulfate complex salt is used to control the number of water mold in the water body, and water mold disease will not occur naturally after the temperature rises and the wound heals. If there is an outbreak of water mold, assess the condition to prevent water mold from infecting other normal fish, and use Primalysis to boost immunity until food is normal and death is reduced.
Precautions for water mildew propagation:
Pay attention to controlling the water temperature. Water temperature is an important factor affecting the occurrence of water mildew, farmers should reasonably adjust the water temperature according to the growth needs of different fish species, and avoid sudden temperature drops or long-term low temperatures. At the same time, it is necessary to monitor the changes in water temperature in real time, and take measures in time if abnormalities are found.
Pay attention to controlling the pH value and the salinity of the water. Keeping the pH value of the water body within the appropriate range is also one of the important measures to prevent water mold. The pH value of the water body can be monitored in real time and corresponding adjustment measures can be taken, such as the use of acid-base regulators, etc., to maintain the pH of the water body. This not only reduces the incidence of water mold, but also contributes to the healthy growth of fish.
It is necessary to pay attention to strengthening water quality management, and measures such as regular replacement of water bodies, monitoring water quality and cleaning up pollutants are necessary measures to prevent and control water mildew. Aquaculture water exchange is also a science, and finally, daily management measures should be strengthened. It is necessary to scientifically feed feed, do a good job in fish disinfection and strengthen daily pond patrols, and find and deal with problems in a timely manner.