Disinfection is the process of eradication of disease-causing microorganisms, the chemicals which are employed to eliminate pathogens are called disinfectants. The target range of each disinfectant is different, so one kind of disinfectant can’t kill all the microorganisms. Various disinfection methods are used worldwide to ensure the safety of organisms by reducing the scale of transmission of diseases. As we know, fishes in aquaculture are more exposed to diseases transmission, thus the use of chemical disinfect is adequate to inactivate the pathogens on all surfaces except living tissues. Proper disinfection should be done for securing high productivity and financial profit.
The process of disinfection is not just applying any chemical disinfectant to the culture water. It is a huge process where the disinfection starts from the fish eggs and ranges to the staff in fish farming. The fundamental protocol in disinfection is the elimination of all disease-causing microbes. Then the remaining organic matters sticking to the surfaces are removed, the equipment and the installation are disinfected, and a final chemical neutralization is done. The following are the methods of disinfection in different targeted objects.
Disinfection of eggs and larvae
Iodine products (iodophor) are the most common chemical used to disinfectant eggs and larvae in aquaculture. It is necessary to conduct a preliminary test to determine at what stage of eggs and iodophor concentration, the disinfection can be safely carried out. Even though iodophor can be used in many species, it is most commonly used in the fish eggs of the Salmonidae family. Even though Iodophor can disinfect the surface of newly and fertilized eggs, it cannot prevent the vertical transmission of the bacterial and viral pathogen(eg, Renibacterium salmoninarum and infectious pancreatic necrosis virus) as the pathogen are present within the fertilized eggs.
Disinfection of materials and equipment with chloramine T, formalin etc
The materials and equipment should be unique for each culture unit since there are chances of contamination. Chloramine T and the formalin are the widely used disinfectant for equipment and materials in aquaculture. The containers used for feeding and mortality collection must be different and should be washed and disinfected regularly. It is better to avoid the transportation of machinery from one aquaculture system to another to prevent any chance of cross-contamination. Machinery that is allowed to be transported in exceptional cases can enter only after washing and disinfection with authorized products. The rest types of machinery used should be disinfected before entry to and exit from farms.
The vehicles which are permitted to the production areas or transit zones should posses a disinfectant certificate. And other vehicles entering the sites must be properly washed and disinfected. Staffs have to put protective clothing( e.g. coat, gloves, apron, boots, etc)and boots and hands should be sanitized before entering the production sites. It is strictly prohibited to enter the sites without authorized protective clothing.No one is allowed to exit the premises wearing a working outfit even if they are subjected to sanitization.
Disinfection of source water and water pipelines by chlorination
Chlorination is a common practice in aquaculture for the disinfection of water and tanks for fishes. The water used in fish farming should be filtered and chlorinated regularly as the source water may contain vectors or carriers of many diseases. The regular disinfection of the pipelines and tanks are highly suggested. Following the harvest, the loose objects, large debris, feaces left overfeed, should be removed. It is suggested that after harvest all non-porous corrosion-resistant equipment should be immersed in the tank for treating with calcium hypochlorite overnight. The tank is then washed with chlorinated water, later the tank is allowed to dry. Chlorine should be handled with intense care because sometimes it could be toxic for the fishes and the workers.
The aquaculture practices should be maintained properly for the viability of this industry, so only scientifically approved products are employed in the culture units. The disinfectants used in aquaculture should possess little or no hazard to the environment and human safety. The workers of aquaculture must follow proper management of disinfectants such as dosage, storage, the period of withdrawal disposal, etc to ensure safety. Uses of chemicals should be properly recorded as suggested by the method of HACCP( Hazard analysis and critical control point). Aquaculture is a developing industry hence it needs to ensure safety in every step of it’s production for sustainability.
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