CATDOLL : CATDOLL: Grass carp enteritis mainly occurs from June to November every year. What are the symptoms?

Grass carp enteritis mainly occurs from June to November every year. What are the symptoms?

How to treat grass carp enteritis

Grass carp enteritis is a relatively serious disease among grass carp diseases. It is known as the "three diseases of grass carp" along with red skin disease and gill rot. The mortality rate of enteritis is relatively high, usually up to about 50%, and up to 90% in severe cases. Therefore, enteritis is also a disease that farmers are most concerned about.

Enteritis of grass carp often occurs at temperatures above 18 degrees Celsius. It is usually prevalent from April to October, with the peak period of the disease being from July to September.

The main causes of the disease are the deterioration of living conditions, the deterioration of water quality and turbidity, the decrease of oxygen content in the water, the increase of ammonia nitrogen, or the long-term consumption of inferior feed or spoiled and moldy feed. Some are caused by mechanical damage to the fish body, which leads to a decrease in resistance. All of the above reasons may cause the fish body's resistance to decrease, at which time the bacteria will multiply in the fish body and the disease will soon break out.

Symptoms of the disease: The fish's body turns black, it is slow to react, swims alone, and does not eat. In severe cases, the abdomen becomes enlarged, the anus becomes red and swollen, or yellow or red pus and blood flow out of the anus, the internal organs are filled with water, and the intestines are purple-red.

The first preventive measure is to disinfect and sterilize the pond, change the water more often when the temperature is high, turn on the aerator more often to ensure the dissolved oxygen in the water, and avoid mechanical damage to the fish.

After enteritis occurs, the first thing to do is to sterilize and disinfect. You can use chloramine or strong chlorine to spray the whole pond. The concentration of chloramine after use is 0.5 grams per cubic meter, and the concentration of strong chlorine after use is 0.3 grams per cubic meter.

In addition, oral medication can be used. For every 100 kg of fish, 500 g of garlic can be crushed and mashed, and 400 g of salt can be added to the feed for feeding. Feed it continuously for 4-5 days. You can also crush 2 kg of fresh purslane for every 100 kg of fish and mix it into the feed for feeding continuously for 3-4 days. You can also add 3 g of compound sulfamethoxazole per kg of feed for feeding continuously for 4-5 days, but please note that you can double the dosage when using the medicine for the first time.

In the early stage of the disease, the symptoms of the fish are not obvious, so it is difficult to detect if you don't pay attention. Some fish eat normally. However, there are some abnormal characteristics that can be distinguished, such as the slow swimming speed of the fish, the blackening of the fish body, and some fish will lose appetite at this time.

Nausea, vomiting, congestion, and redness and swelling of the anus, etc., are all symptoms and are very dangerous. There may also be some bacteria in the body.

The symptoms of grass carp enteritis are: the belly of the grass carp is swollen and bulging, there will be red spots on both sides, the anus will be red, swollen and protruding, the intestines will be inflamed and congested, and even bleeding, the intestinal wall will become thinner and the elasticity will decrease.

Symptoms of grass carp enteritis include slower swimming, blackening of the fish body, swollen abdomen, and protruding anus. If the fish shows these symptoms, it must be treated promptly.

What causes grass carp hepatobiliary syndrome?

According to current research results, the causes of grass carp hepatobiliary syndrome are mainly divided into three categories: feed factors, environmental factors and drug factors:

1. Nutritional factors that cause grass carp hepatobiliary syndrome:

1.1 The protein and carbohydrate content of feed is too high. The excess protein and carbohydrates are converted into fat in the liver through a series of transformations and accumulate in the liver, especially the accumulation of neutral fat, which will lead to excessive liver fat accumulation, hepatocyte cavitation, hemorrhagic necrosis of hepatocytes, and interfere with the normal nutritional metabolism of fish. When fish eat feed with insufficient polyunsaturated fatty acid content or excessive saturated fatty acid content, triglycerides will accumulate in the liver and the deposition rate of fat in the liver will accelerate.

1.2 Lack of choline in feed

Choline deficiency leads to fat metabolism disorders in fish and slows down fish growth, which in turn causes a significant increase in fat content in the liver and liver damage.

1.3 Feed mildew and feed lipid oxidation

Feed mold or lipid oxidation will produce toxic and harmful substances, such as aflatoxin, rancid fatty acids, etc., which can cause fish liver cell enlargement, gallbladder enlargement and blackening, liver fatty degeneration, liver cell nuclear condensation, causing liver cell damage, metabolic dysfunction and other symptoms.

1.4 Use of non-conventional raw materials in feed

Toxic and harmful substances such as cottonpol in cottonseed meal, glucosinolate in rapeseed meal, and nitrite in inferior fish meal can all cause hepatobiliary diseases in fish.

2. Environmental factors that cause grass carp hepatobiliary syndrome: Overly intensive breeding environment can cause excessive ammonia nitrogen concentration in the water, which makes it difficult for the metabolic products of ammonia in the fish to be excreted normally and accumulate in the blood, causing metabolic imbalance in the fish and leading to hepatobiliary diseases.

3. Drug factors that cause grass carp hepatobiliary syndrome: Drug abuse is common in aquaculture, such as adding furazolidone, chloramphenicol, sulfonamides, etc. to feed in low doses and for a long time, or using fish medicines with large side effects and high residues such as trichlorfon and copper sulfate, which can cause liver damage to grass carp.

Regardless of the factors of feed, environment or medicine, the main cause of grass carp hepatobiliary syndrome is the obstruction of fat decomposition and metabolic function, which leads to the gradual loss of liver and gallbladder function. The liver is the largest gland in fish and the most important metabolic organ. In addition to secreting bile to help digestion and absorption, it can also synthesize absorbed nutrients into glycogen, fat and protein. It also plays an important role in detoxification, vitamin storage, immunity, etc. Once it is damaged or pathological, it will lead to metabolic disorders, decreased immunity and disease resistance of the fish body, and it is also very easy to cause secondary infectious diseases, which seriously threatens the healthy breeding and development of grass carp.

The causes of hepatobiliary syndrome in grass carp include temperature changes, water quality deterioration, decreased resistance, etc.

When liver and gallbladder diseases occur: it will reduce the anti-stress ability of grass carp, because liver dysfunction will inactivate the fish's fibrinogen and thrombin, which will make it difficult for the blood to coagulate when the fish's blood vessels rupture. Once the fish is exposed to stress stimulation (such as pulling nets, transportation, sudden changes in water temperature, poor water quality, etc.), stress hemorrhagic syndrome will occur, and even a large number of deaths will occur; it will cause nutritional metabolism disorders in grass carp, affect the metabolism and absorption of nutrients, affect growth, and increase the feed coefficient; it will cause the immune system of grass carp to be disordered, resulting in a decrease in the disease resistance of grass carp, making it more prone to large-scale infectious fish diseases such as hemorrhagic disease, gill rot and enteritis.

Prevention and treatment measures for hepatobiliary diseases:

(1) Feed scientifically. Choose nutritious, comprehensive and high-quality feed. Avoid overfeeding to prevent the spoilage of miscellaneous fish and the feed from getting damp and moldy.

(2) Reasonable density should be adopted to regulate water quality. The stocking density of grass carp should be determined according to the water depth, bottom conditions, water source and feed supply, and breeding level of the fish pond, so as to prevent the water quality environment from affecting the healthy growth of black carp.

(3) Daily prevention and treatment, correct use of drugs. Prevention is the key to the treatment of liver and gallbladder diseases in grass carp. Once the disease progresses to the point where the patient stops eating, it is difficult to treat and cure. Early prevention and treatment are necessary. When using drugs, do not add low-dose, long-term oxytetracycline, sulfonamides, tetracycline antibiotics and other drugs that are harmful to the liver of fish to the feed. Do not blindly use bromomethrin, trichlorfon, copper sulfate and other fish drugs with large side effects and high residues. Try to identify the pathogen, treat the symptoms and eliminate the cause.

(4) Reasonable addition of Saiko Xiagan Yidan. Regardless of the cause of grass carp liver and gallbladder disease, the addition of Xiagan Yidan is essential. As an endogenous digestive fluid secreted by the liver of vertebrates, grass carp can promote fat metabolism in the liver, promote lipid decomposition, inhibit lipid synthesis, thereby reducing fat deposition in the liver, preventing and treating fatty liver disease in fish; at the same time, Xiagan Yidan can bind to or decompose endotoxins in the intestines, promote the body's detoxification, and prevent endotoxins from harming the intestines, liver and even the entire fish body, thereby preventing and treating drug-induced liver disease and infectious liver disease in fish.