Main symptoms and incidence regularity of Anguilla Anguilla mania

It is caused by eel coronavirus-like virus (EelCoronavirus-likeVirus). The main symptoms of ① disease eel in the pool water up and down or rolling rotation or backward swimming, sometimes paroxysmal head spasm strong tremor or twist, mouth open, soon die. There are no obvious symptoms on the body surface, and sometimes slight congestion or ulcers can be seen in the oral cavity, anal fin and pectoral fin, and enlargement of the liver or kidney can be seen by dissection. In the early stage of ②, a small number of eels swim irregularly at the edge of the pool, swimming weakly, with interstitial head twitching, rotation and rolling or backward movement. A few days later, a large number of eels developed similar symptoms with paroxysmal head tremors and died soon after swimming wildly on the surface of the water. The newly dead eel was stiff and its mouth was open. The body surface of the diseased fish is intact, but there are varying degrees of ulcer or congestion in the lower jaw. Some diseased fish have congestion or ulcers in the mouth, anal fins and tail. The Gill filaments of most diseased fish are bright red, the liver is light red, and the kidneys of some diseased fish are enlarged. The red blood cell, hemoglobin and serum chloride ion of diseased eel increased significantly, while the content of blood urea nitrogen and serum cholinesterase decreased significantly. At present, due to the lack of in-depth understanding of the disease, it can only be diagnosed according to the above-mentioned main symptoms. It mainly occurs in European eel and African eel, and the high temperature in summer is the peak season of epidemic, so it is also called European eel summer wandering disease. From the beginning of the disease to the peak period of about 7 days, a large number of deaths in about 15 days after the onset of the disease, spread very fast, easy to form an outbreak.