Key Technical Points for Disease Prevention and Control in Pollution-Free Fish Farming

Symbiosis of plants and animals: When aquatic plants and fish live together in the same pond, the fish rarely get sick. The aquatic plants planted in the fish pond are rice or lotus roots, arranged in an east-west direction, with wide row spacing (greater than 33 cm), occupying no more than 50% of the total water area so that the lighting effect is good. The water depth depends on the water tolerance of the aquatic plants; for rice it is generally within 30 cm, and for lotus roots it can generally reach more than 50 cm. The farmed fish can be conventional species or famous, special and improved new varieties. The farming method can be seedling breeding or adult fish farming. Because residual bait, fish feces and so on are deposited at the bottom of the pond, ferment and rot, not only polluting the water quality but also easily breeding harmful pathogens. The aquatic plants, however, can absorb them as fertilizer, eliminating the breeding grounds of pathogens, so the incidence of disease in the fish is low.

Sprinkling Chinese herbal medicine: On rural hillsides, by streams and roadsides there are many Chinese herbal medicines, such as pine needles, camphor leaves, hemp willow leaves, Chinaberry, Acorus, Chinese gall and so on. When dead fish float on the surface of the fish pond, when the fish suddenly stop feeding for reasons other than weather, or when some fish swim alone away from the school, you can collect, or regularly collect, the above Chinese herbal medicines, 15-30 kg per mu. Set up a large pot at the pond edge, cut the collected Chinese herbal medicines into small sections about one cun long, put them into the pot, add clean water and boil them. After boiling, sprinkle them into the pond together with the liquid. After 12 hours the water color turns brown, and it is non-toxic and harmless to the fish and water quality. It will quickly bring the possible spread of potential fish diseases under control or prevent the occurrence of fish diseases.

Ecological disease prevention: In practice it has been found that in the ecosystem of a fish pond, if the biological species in it are more numerous and complex, the ecosystem is more sound, and the disease resistance of the system is stronger. If few species are farmed in the fish pond and a single species accounts for more than 50%, that species is often prone to disease. In polyculture, however: grass carp, common carp, crucian carp, large-mouth catfish, snakehead, silver carp and bighead carp, Chinese softshell turtle, tortoise, eel, as well as unavoidable wild trash fish, snails and mussels coexist in the same pond. Each species has a different ecological niche, and complex food chain relationships exist. Due to the "gudgeon effect", carp and crucian carp dig at the pond bottom while searching for food, destroying the environment in which pathogens easily breed. Diseased fish, because of their slow movement, are eaten by carnivorous fish, cutting off the transmission routes of pathogens. The ecosystem automatically prevents disease, so the incidence of disease in the pond is low.

Toads preventing fish diseases: From many years of observation, when there are many toads in and around the fish pond, the fish in the pond rarely get sick, because toad venom can eliminate and kill pathogens in the pond. In fish ponds that are not easy for them to escape from, you can directly catch toads and put them in; in fish ponds that are easy for them to escape from, use bamboo baskets or net bags to enclose them and put them in, preferably at the water inlet, at least 5 per mu per pond. It is best to release the enclosed toads after 3 days to avoid death. Toads are more numerous in towns by riversides where plants are lush, and can be found at night with a flashlight; their escaping ability is not strong, and they are very easy to catch. After 2-3 years of catching toads to prevent and control fish diseases and then releasing them, the toads in and around the pond will increase year by year, and they can naturally effectively prevent the occurrence of diseases in the fish pond.