Prevention and treatment of spasmodic disease of Monopterus Albus

As the artificially propagated seedlings of Monopterus Albus can not be produced in large quantities at present, the breeding of Monopterus Albus still depends on the wild seedlings caught naturally, while the sources of wild seedlings are different, coupled with improper operation and other factors, soon after release, the phenomenon of spasms in Monopterus Albus is very common. The death rate of spasm of Monopterus Albus is quite high, which causes great losses to farmers. The causes and preventive measures are briefly introduced as follows.

Symptoms of spasmodic disease of ricefield eel

Spasms generally occur 2-10 days after the wild eel seedlings are stocked. At first, the eel seedlings do not eat and are easily frightened. After hearing the sound and vibration, the eel seedlings will swim and jump, and it will last for a few minutes before they tend to calm down. After 2-3 days, the eel seedlings began to show bending symptoms and exercise in circles on the spot. at the same time, the muscles were extremely tense, the head and body showed "S" or "O" type irrecoverable contraction, and involuntarily bit themselves, and 4-5 days later, the eel seedlings began to die. The body surface examination of diseased eel seedlings did not have any symptoms of inflammation and congestion, visual and microscopic examination showed that there were no parasites on the body surface, and there were no pathological changes in internal organs, but the blood was darker red than normal, a large number of echinococci were found in the intestines and capillary nematodes were found in the abdominal wall of the infected eel. However, most of the wild ricefield eel parasites have the above parasites, so the pathogenic factors of parasites can be excluded. From the beginning of persistent illness to the end of death, the time is about 7-20 days, the mortality rate is generally more than 30%, severe cases can reach 100%.

Etiology of spasmodic disease of Monopterus Albus

The cause of spasm of Monopterus Albus is mainly due to the decrease of blood oxygen-carrying capacity of Monopterus Albus, which leads to insufficient oxygen supply to the brain, brain hypoxia and brain necrosis, and high concentration of ammonia and hydrogen sulfide into the blood of Monopterus Albus, resulting in blood poisoning.

1. Fishing. In the rainy season, after the cage for catching ricefield eel is submerged, the ricefield eel entering the cage has a stronger metabolism due to feeding on the bait, coupled with the increase in oxygen consumption during the struggle, the oxygen it breathes in the water can no longer meet the needs of the body, and air breathing can not be realized, resulting in obstruction of carbon dioxide excretion in the body, an increase in carbon dioxide accumulation in the blood, resulting in blood acidosis, and in serious cases, Monopterus Albus died when it was caught. But most of them are still alive, and the probability of spasms in this kind of eel seedlings is very high.

2. Storage. After fishing, the storage density of Monopterus Albus is generally high, the ratio of water to Monopterus Albus is less than 1 ∶ 1, and the water is not changed for a long time. Under the condition of high density, Monopterus Albus constantly secretes mucus and excretes metabolites, which decompose into poisonous and harmful gases such as ammonia and hydrogen sulfide under the action of bacteria. These poisonous and harmful gases breathe into the blood through the skin of Monopterus Albus, causing blood acidosis.

3. Transportation. Dry transportation had a more severe effect on eel seedlings. Due to the lack of moisture, eel seedlings lost the carrier of gas exchange, and the respiration was seriously inhibited, even to the degree of asphyxia. At the same time, the mucus and excreta secreted by eel seedlings will produce high concentration of hydrogen sulfide because there is no dilution of water. The harm caused by this link is more serious than that of high-density storage, because this process is accompanied by the dehydration process of body fluid loss. Generally, the probability of spasm of eel seedlings transported by dry method for more than 2 hours is more than 90%.

4. Other reasons. The difference in water temperature during acquisition, storage, transportation and stocking is too large, resulting in metabolic imbalance of Monopterus Albus, commonly known as "cold", and the formation of a barrier in the body, so that carbon dioxide in the body can not be excreted, resulting in high concentration of carbon dioxide in the blood. cause blood acidosis.

Prevention of spasmodic disease of Monopterus Albus

1. Avoid purchasing eel seedlings in the rainy season, reduce transit links, purchase eel seedlings directly from rice field eel fishermen, and avoid buying eel seedlings from markets and vendors.

2. The eel seedlings purchased should be caught on the same day, and the fishers are required to store the eel seedlings in water that is more than 5 times the weight of Monopterus Albus, so as to avoid the long-term storage of Monopterus Albus.

3. When eel seedlings are transported with water, the ratio of eel seedlings to water is at least 1 ∶ 5. If long-distance transportation needs to use drugs to protect water quality, some polysaccharides, multivitamins or antibiotics can be added properly to avoid soaking with irritant drugs such as chlorine agents and oxidants.

4. Avoid excessive water temperature difference in the links of acquisition, storage, transportation and stocking.