Prevention and treatment of fish hepatobiliary syndrome in summer

With the emergence and development of high-density, intensive breeding models, the breeding environment is deteriorating day by day, and fish diseases are frequently outbreaks and epidemics, resulting in the emergence of new fish diseases characterized by hepatobiliary diseases, namely fish hepatobiliary syndrome. Hepatobiliary syndrome has always been one of the fish diseases that plague aquaculture, the epidemic season mainly occurs from June to October, has been widely spread throughout the country, especially fry, fish species incidence is high, the main objects of harm are carp, crucian carp, grass carp, spotted forktail catfish, cloud catfish, snakehead, rainbow trout, split-bellied fish, tuantou bream, bluefish, tilapia, also commonly found in turtles. Due to the widespread misdiagnosis of other fish diseases, the medication is not correct, and the mortality rate can reach 50%-60%, and even up to 60%-90%.

　　Triggers for fish hepatobiliary syndrome:

　　1 Feed recipe. As the temperature rises, the fish begin to enter the peak growing season and have a strong appetite. However, the feeding of 3 high feeds (high protein, high fats and high carbohydrates), the difficulty of digestion of fish increases the burden on the liver and gallbladder. At the same time, high-protein feed is easy to induce liver fat accumulation, destroy liver function, interfere with the normal physiological biochemical metabolism of fish, and the carbohydrate content is too high, which will cause fish sugar metabolism disorders, causing visceral fat accumulation, hindering normal function, its main lesion site is the liver, a large number of liver sugar accumulation and fat infiltration, resulting in hepatomegaly, color fading, dull appearance, serious fatty liver can also cause liver lesions, so that the liver loses normal function, therefore, there is a fish disease with hepatobiliary disease as the main feature, i.e. fish hepatobiliary syndrome.

　　2 The breeding density is too large and the water environment is deteriorating. The use of a large number of antibiotics causes drug residues to accumulate a large number of endotoxins, and in the high-density breeding mode, the concentration of ammonia nitrogen in the water body is too high, and the metabolites of ammonia in the fish are difficult to discharge normally and accumulate in the blood, causing the imbalance of fish metabolism and causing hepatobiliary diseases.

　　Hazards of fish hepatobiliary syndrome:

　　1 When the liver and gallbladder of the fish are malfunctioning, a series of diseases such as the end of the fish's filaments are white, the scales and skin are rough, the tail fin is white, the eyes have blood spots, the intestines are congested, and the immunity is low.

　　2 Serious lesions and damage to the liver, gallbladder and other major organs of the diseased fish body, resulting in a decrease in the amount of fish ingestion, and even the phenomenon of non-feeding, the body's disease resistance declines, and other pathogenic bacteria are more likely to infect the fish body, often accompanied by bleeding, gills, enteritis, rotten tail and other symptoms.

　　3 The rate of pond exit has decreased and the transport mortality rate has increased. The hepatobiliary mechanism of the fish body decreases, the ability to resist stress is reduced, and the mortality rate increases.

　　The role of bile acids in the prevention and treatment of hepatobiliary syndrome:

　　1 Bile, as one of the three major digestive juices, can promote the digestion and absorption of fat and improve feed utilization. Thus helping to reduce the high pressure and burden caused by the difficult digestion and absorption of the three-high feed on the fish liver and gallbladder, reduce the damage of liver cells, and maintain the normal fat metabolism of the body.

　　2 Bile acid is both a digestive juice and a excretion fluid, the addition of feed bile acids can promote the secretion of bile, the presence of goose deoxycholic acid components can decompose endotoxins, excrete excessive fat and heavy metals adhering to liver cells, reduce the deposition of fat in the liver, prevent fish fatty liver, thereby improving the function of the hepatobiliary mechanism of the fish body.

　　Once the hepatobiliary mechanism of the fish body declines, on the contrary, it will affect the fish's organs such as cats, scales, skin, eyes, intestines, immune system, etc., bacteria, viruses, toxins, etc. in the fish body and outside the fish will take advantage of the void and cause a variety of diseases, so we are very tricky in the treatment of hepatobiliary syndrome, because antibacterial, antiviral, and insecticides are basically ineffective, this is only a symptom, not a cure. As the saying goes, the outside must first be inside. Therefore, protecting the health of the fish body and improving the hepatobiliary mechanism is king.

　　Necessity of adding feed bile acids:

　　In today's intensive breeding, on the one hand, aquatic animals themselves have insufficient bile acid secretion, on the other hand, the amount of feed oil and fat is getting higher and higher, which greatly increases the incidence of aquatic hepatobiliary syndrome.

　　As the temperature gradually rises, the fish enter a stage of rapid growth, accompanied by an increase in feed intake is a decrease in the hepatobiliary mechanism. Therefore, the addition of exogenous bile acids is particularly necessary.

　　In addition, the prevention and treatment of aquatic hepatobiliary syndrome should also be carried out from the two aspects of feed and water quality, scientific design of feed formulas, selection of high-quality raw materials, and strengthening of water environment management.