Mandarin fish, because of its delicious meat and rich nutritional value, popular with consumers. However, in the process of Mandarin fish farming, the threat of parasitic diseases cannot be ignored. In this paper, several common Mandarin fish parasitic diseases and their prevention and control measures will be introduced in detail to help farmers better protect the health of Mandarin fish and improve aquaculture efficiency.
1. Common parasitic diseases
Balantidiumcoli
Symptoms: The naked eye can see that the sick fish has a grayish white substance on the head, the mouth is open, and the swimming loses its balance and sinks in the water, and then dies. The disease spreads very fast and does the most harm to Mandarin fish fry.
Prevention and control measures: Use copper sulfate and ferrous sulfate to splash the whole pool to kill ciliates and keep the water clean.
Sinergasiliasis
Symptoms: Is a large white elongated worm visible to the naked eye. It parasitic on the surface of fish, causing inflammation, congestion and erythema, especially in young fish.
Prevention and control measures: ① the pond should be thoroughly cleaned after fish cleaning; ② The fish species stage uses crystal trichlorfon (90%) 0.25-0.5 g/m3, but the adult fish stage is sensitive to trichlorfon (when the concentration is 1 heng liter, the fish begins to die 8 hours, and the mortality rate reaches 100% within 48 hours), and the use should be cautious.
Melon worm disease (white spot disease)
Symptoms: The gill filaments of the sick fish are dark red, the fins and body are covered with white spots, the infected fish body surface and gill parts secrete a lot of mucus, and the fish dies due to breathing difficulties. The disease mainly affects fish under 5 cm.
Prevention and control measures: (1) The pond should be thoroughly disinfected with quicklime and have a reasonable stocking density to maintain sufficient dissolved oxygen and good water quality; ② Soak the sick fish in 2% salt water for 10 to 15 minutes; ③ 2 g/m3 of methylene blue is sprinkled in the whole pool; ④ The whole pool is sprayed with formaldehyde solution 0.015~0.025 ml/l.
Dactylogyrus disease
Symptoms: Diseased Mandarin fish swim slowly with floating head, black body color, significant edema of gill, gill lid open, gill filaments showing light red and mucous, and bacterial rotten gill disease is complicated in serious cases, which is more serious in summer and autumn.
Prevention and control measures: ① Disinfect the fish when they are in the pond and in the water, such as thoroughly disinfect them with 3% salt water or 0.15 ml/l formaldehyde solution; (2) Scientific feeding to reduce water pollution; ③ Use insect repellent once every half month; ④10% mebendazole + Fuzhan Jiedu powder can inhibit or kill insects.
Wheel worm disease
Symptoms: The sick fish does not eat food, the body color is dark, lustrous, swimming alone, moving slowly, and sometimes scurring, a large amount of mucus can be seen in the gills and a large number of insect bodies can be detected by microscopy.
Prevention and control measures: ① Disinfect fish seed, water and bait fish when they enter the pond (such as 0.15 ml/l formaldehyde solution); ② The use of biological and chemical methods to promote the bottom material to an oxidation state; ③ The whole pool was sprayed with 0.7g/m3 mixture of copper sulfate and ferrous sulfate (5:2). Two days later, the nymphs were not killed by microscopic examination, and continued to be sprayed once; If there is no effect after two sprinkles, stop using the drug.
2、comprehensive prevention and control measures
① Water quality management regularly test the water quality, keep the dissolved oxygen in the water body sufficient, and maintain the pH value between 7.5-8.5.
② Clean the pond regularly and fish out the dead fish in time to prevent the deterioration of the water quality.
③ Scientific feeding of Mandarin fish as a benthic fish, life to live fish (shrimp) for food, to ensure that the supply of bait fish is sufficient and fresh.
④ Reasonable control of stocking density to avoid water quality problems caused by too many fish.
The pond, fish species, bait fish and breeding tools should be regularly disinfected to reduce the spread of pathogens.
Use quick lime, potassium permanganate and other disinfectants to ensure disinfection effect.
⑦ Drug prevention Use safe and effective drugs such as vino Deworming, sprinkle the pond regularly to kill parasites.
⑧ Pay attention to the safety of drug use to avoid adverse effects on fish and water quality.
⑨ Daily management Patrol ponds every day, observe the activity of Mandarin fish, timely discover and deal with abnormal situations.
⑩ Equipped with aerator to ensure sufficient dissolved oxygen in water and improve the growth rate and survival rate of Mandarin fish.
The reason why the diseases and pests of the Mandarin fish occur frequently is that its resistance to diseases is relatively weak. Once infected with diseases and pests, it is often difficult to cure, which brings huge economic losses to farmers. However, the traditional pond farming mode is vulnerable to the invasion of bacteria and parasites due to the open environment and extensive management.
Today, the factory aquaculture model can effectively prevent and control the occurrence of diseases and pests through scientific management and advanced technical means. The comprehensive use of closed plant design, circulating water system, temperature control system, oxygenation system and sterilization and disinfection system creates a stable and healthy growth environment for Mandarin fish. In such an environment, the disease resistance of Mandarin fish is significantly improved, and the occurrence probability of diseases and pests is greatly reduced.