Application of medicinal plants in prevention and control of aquatic animal pathogens

Medicinal plants are rich in active ingredients, including polysaccharides, alkaloids, flavonoids, volatile oils, organic acids, tannins, as well as nutrients such as amino acids, carbohydrates, minerals and vitamins. Compared to traditional antibiotics, medicinal plants have the excellent advantages of being natural, efficient, cheap, nontoxic or less toxic, easy to obtain, and having little side effects on farmed animals and the cultured environment. Moreover, drugs prepared from medicinal plants and their extracts rarely produce drug resistance, which is considered as an effective substitute for antibiotics. In view of the application values of effective medicinal plants ingredients against diseases in aquaculture, this paper focused on the latest research progress of medicinal plants in combating bacterial, viral and parasitic pathogens in aquaculture, and serve as an immunopotentiators to regulate aquaculture animals. It was noting that, at present, there were many medicinal plants-based fishery functional products in China, but they were not strong in effects.Moreover, the following problems still existed in the application of these products in aquaculture.① The bioavailability of active ingredients of medicinal plants was affected by the growth stage and place, and it was difficult to identify the exact dosage of medication.② Researches on the action mechanism of medicinal plants were relatively rare, the components of traditional compound medicinal plants preparations were complex, and the mechanisms of synergy and antagonism between different medicinal plants were not clear yet.③ The quality of Chinese herbal medicines of the same variety and different producing areas was inconsistent, and the efficacy differences were obvious in actual use. Therefore, in the future, in-depth researches should be carried out on the effective components, action mechanism, use mode, combination ratio and compound dosage forms of medicinal plants, as well as the quality control of Chinese medicinal herbs, so as to give full play to the role and value of medicinal plants in aquatic diseases prevention and control, and further develop a group of high-efficient green disease-resistant fishery medicines by using medicinal plants. It could greatly improve the substitution rate of chemical drugs, and effectively reduce the losses caused by aquatic diseases, so as to ensure the highquality development of aquaculture in China.