The status of drugs in the prevention and treatment of fish diseases.

The status of drugs in the prevention and treatment of fish diseases.
At present, the prevention and cure of disease in farmed fish, the agriculture, fisheries and conservation is the main use a variety of drugs, and some even completely dependent on drugs and fish not sick with drug prevention, sick with drug therapy, and often use multiple drugs at the same time or take turns, for other control measures is rarely considered. However, it should be known that in the pond a large number of drugs used in the presence of many ills, such as pollution of the environment, the poison of the drug to the fish, the residues of drugs in the fish body and the drug resistance of the pathogen, etc.. Actually, the prevention and treatment of fish diseases in addition to drugs, there are a variety of methods can comprehensive use, totally dependent on drugs can not solve the problem of. Therefore, the most important for breeders is to improve the breeding technology, strengthen the management, the use of comprehensive measures to reduce the occurrence of the disease, thereby reducing the use of drugs, do. No disease prevention, early treatment, prevention and treatment.
Infectious diseases of fish are the result of interaction between pathogen, fish and environment. Following from these aspects analysis the causes of disease, and introduces the main methods and Countermeasures for the prevention and treatment of fish diseases.
1 fish body
The occurrence of the disease must also have two conditions, namely, susceptibility and resistance to decline. That is to say, only when the water body of the fish can be infected with the pathogen, while the fish’s resistance to disease and decline, it is possible to attack. Susceptibility is mainly related to fish species, age and so on. For example, silver carp, bream fish not infected grass carp hemorrhage of reovirus from, grass carp, although can be infected with the virus, but Ctenopharyngodon idella this virus is not easy. Therefore, in the process of disease prevention and control of this link, the following measures can be used.
New varieties of fish (1) breeding for disease resistance and strong fish a fish disease resistant force and strength of this kind of pathogen sensitivity is determined by genetic factors. Therefore, we can fish species breeding natural immunity, can also use molecular biology technology breeding disease resistant force is powerful, many of our scientific research units are engaged in the research, at present focus in grass carp. This is because the grass carp is a kind of high quality fish in China. It grows fast and has a low cost, but the disease is the most of the fish. As a breeding unit, we should pay attention to the information, timely introduction of resistance to strong fish, in order to improve the breeding efficiency. Moreover, it is necessary to recognize that the new breed of disease that has already been developed or cultivated in the future is just a resistance to some disease, but it is not possible to resist all diseases. But we still can according to the different breeding fish to certain diseases have different resistance this principle to guide preventive culture, for example, can the harmonious culture of grass carp, bighead carp, crucian carp, carp and other to reduce or avoid the occurrence of hemorrhagic disease of grass carp, reduce the silver carp and big head carp outbreaks of fish diseases.
(2) artificial immune system is a very hot research field at home and abroad, the main use of active immunization, active immunization with inactivated vaccine and attenuated vaccine, in foreign countries have been commercialized fish vaccine. The use of vaccines can be targeted to improve the resistance of the body to a certain or some of the pathogen. For example, through the injection of Grass Carp hemorrhage tissue vaccine can prevent the occurrence of pulp, Grass Carp hemorrhage. This technology has been widely used in China, but due to the lack of a simple and effective way of immunization, which makes the practical use of immune disease prevention technology has been greatly affected. This is because the use of injection method, time consuming, and the damage to fish. In addition, the immune effect of the vaccine is affected by many factors, such as the production process, the use of concentration or dose, the immune pathway and the procedure. Even if it can achieve the desired effect, but because of the specificity of the vaccine is too strong, it can only prevent one or several (for many vaccines) disease, not to prevent the occurrence of other diseases.
(immune enhancement agent used in the feed to add polysaccharide or some Chinese herbal medicine, long-term feeding can improve the fish specific immune and non-specific immune function, so as to enhance the resistance to disease. At present, the domestic and foreign markets have fish with immune enhancement agent supply.
(4) using reasonable feed is one of the most basic means to improve the resistance of fish. Breeding fish if long-term malnutrition, or lack of certain vitamins or trace elements, will seriously affect the fish’s disease resistance, which can induce the occurrence of disease.
In addition, the stress response of fish should be avoided in the process of breeding, because the stress response of long time can result in the decrease of the resistance to the fish, and increase the susceptibility to various pathogens.