Cage Disease Prevention and Control Measures in Northern Cage Farming

In northern China, the use of water resources in valley-type reservoirs and abundant wild fish resources for catfish cage culture is a good project for the fishermen in the reservoir area to become rich. The culture of cage culture is relatively fresh and the incidence of fish is relatively small. However, it is difficult to control disease in cage culture. First, because of high stocking densities, infection will occur once the disease occurs, and the disease will be severely damaged in a short time. Second, the water is constantly being exchanged between the inside and outside of the tank, and the use of drugs is difficult, and the medicine is difficult to achieve. Effective concentration and action time required for disease prevention and treatment; In addition, carp only eat live baits, disease treatment is more difficult. The following describes the disease prevention and control technology of cage cultured salmon:

First, disease prevention measures

1. Strictly control seedling quality. Before the stocks are stocked, a comprehensive quality inspection is required to ensure that the stocks of the stocked salmon are robust and do not carry pathogens themselves, thus laying a solid foundation for future breeding. The seedlings should be immersed and sterilized before entering the box to kill the pests and diseases on the fish.

2. Science feeds bait fish. To prevent the occurrence of carp disease, the first thing is to prevent and control the disease of the good bait fish, and at the same time, strict bait fish disinfection system. Each batch of bait fish must be strictly inspected to prevent the introduction of pathogens, and resolutely put an end to pathogens through the bait fish. Adhere to feeding bait fish according to the principles of timing, quality, and quantity.

3. The stocking density should be suitable. The stocking density should be appropriate. If the stocking density is too large, it will increase the probability of occurrence of fish disease. If it is too small, it will affect the yield. When cultivating fish species, first choose a sturgeon seedling with a length of 3 cm or more into a no-nodular net cage with a mesh of 20 mesh/cm 2 , and raise the average stocking density to 200 to 300/m 2 ; When the average tail-tail weight of squid reaches more than 10 grams, it is transferred into a knot-free cage with a mesh size of 1.5-2 cm, and the stocking density is 80-100 tails/m2. When the adult fish are cultured, 100 to 150 g of carp species are placed in a cage with a mesh size of 3 cm, and the stocking density is 15 to 20/m2.

4. Strict management. Observe daily observations of food intake and activities of farmed fish. If any abnormalities are found, take timely measures to deal with the situation. Pay attention to improving the aquaculture water environment, ensuring smooth water circulation, timely removing the dirt attached to the cage, and removing the sludge and diseased fish in the tank. Regularly scrub the wall, float and replace the clothing. Manually cleaning cages is relatively laborious and can be used to hold a certain amount of scraping fish, such as yellow-tailed mires, tilapia, etc. This can greatly reduce the labor intensity of washing, prevent clogging of the mesh, and keep the exchange of water inside and outside the box unobstructed.

5. Disinfect regularly. Carp is a ferocious fish, only eat live fish, live shrimp, oral administration of drugs can only be indirectly through the bait fish, the effect is relatively poor. Therefore, we must adhere to the principle of “prevention first, prevention and control combined”. From late June to early September, every 20 days, we must prevent disease once and use the “killing insecticide + disinfection + internal medicine” three-pronged disease prevention method.

Second, fish disease treatment

1. Scientifically diagnose the condition. The disease of carp is relatively complex. It mainly manifests as parasitic diseases such as trichodiasis, oblique tuberculosis, and finger ringworm at the stage of fingerlings. It mainly manifests as bacterial diseases such as gills and enteritis at the stage of adult fishes. In addition, a small number of outbreaks of viral diseases, such as leukoplakia, have sometimes caused mixed infections of parasitic diseases, bacterial diseases, and viral diseases. Therefore, once the disease occurs, it is necessary to timely diagnose, identify the cause of the disease, and prescribe the right medicine, select high-quality and low-toxicity fishery drugs, and strive to place the drug in place.

2. Method of administration. To be symptomatic, and to formulate a rational drug plan because of combining weather, water environment and other factors at the same time. Prevention of disease can not be frequent use of drugs, can not arbitrarily increase the dosage or repeated low-dose medication, do not use a single drug for a long time. Specific drug methods are:

1 full box continuous pharmacy method. First spill the drug container and reach a certain concentration. Since the water inside and outside the cage is flowing, additional drugs are required after a certain period of time. The whole box spillage method has a large amount of medication and the effect is not ideal, so it is rarely used.

2 drug bath dipping method. The fish in the cage was caught and placed in another dense-eye cage, and the dense-eye cage was placed in the original cage. Then, according to the prevalence of fish diseases, the medicine was bathed in the medicine bath. With the prolonged immersion time, the drug concentration in the dense-eye cages will also decrease, and additional drugs will be required at intervals. However, due to the small cage size, dense meshes, and fewer drug additions, the amount of drugs used will be greatly increased. cut back. Because the dense mesh cage is placed in the original cage, once the drug concentration has affected the survival of the fish population, the fish in the cage can be returned to the original cage. This has no risk or effect. If the operation is too cumbersome, you can also pave the dense mesh on the bottom of the cage, and then lift the four corners of the cage to allow the fish to be immersed in the bottom of the cage after the drug is immersed. This disinfection effect and the use of dense mesh cages Drug dipping is similar, but labor intensity can be greatly reduced.

3 hanging basket, bag sterilization method. When the fish in the cage is found to have diseases caused by bacteria, protozoa, and crustaceans, disinfection may be carried out using a bleaching bag or a cupric sulfate method. If it is a disease caused by bacteria, it can be filled with 100-150 g bleaching powder (or according to the size of the cage) into a cloth bag. Each cage is hung with 2 to 4 pieces and treated continuously for 3 to 5 days; if it is protozoa or carapace Diseases caused by parasites can be controlled by using copper sulphate. Since the cage is set in a flowing body of water, the use of hanging and hanging bags to prevent fish disease generally does not produce adverse drug reactions to fish.

4 feeding bait law. Through the indirect administration of bait fish, the bait fish size is 50% to 60% of the body length of anchovy. Because it is an indirect medication, the amount of medication used when formulating baits is 3 to 4 times the conventional dose. Before the feeding of the fish, the fish was immersed in 10% salt water for disinfection and the sick, disabled and weak individuals were excluded.

5 smear method. In case of salmon trauma or red skin disease or watery mildew, the drug can be applied in conjunction with the examination. The method is to mix the medicine with petrolatum to make an ointment and apply the wounded parts of the fish body. This is a better method of prevention and treatment.

6 injection method. Intramuscular injection is one of the most effective methods of medication. In recent years, when cages are farmed, vaccines for stocking fingerlings or adult fishes have good disease prevention effects. If you use a metal continuous syringe injection, you can improve efficiency and save liquid medicine.

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