Pollution-Free Fish Disease Prevention and Control Methods and Technical Key Points

Animal-Plant Symbiosis: Aquatic plants and fish coexist in the same pond, and the fish rarely get sick. The aquatic plants planted in the fish pond are rice or lotus root, oriented east-west, with a 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; rice is generally within 30 cm, while lotus root can generally reach over 50 cm. The farmed fish can be conventional or famous, special, and excellent new varieties. The farming method can be fry rearing or grow-out fish farming. Because residual bait, fish feces, and other matter deposit at the bottom of the pond, ferment, and rot, they not only pollute the water quality but also easily breed harmful pathogens. Aquatic plants, however, can absorb them as fertilizer, eliminating the breeding grounds for pathogens, so the fish disease incidence rate is low.

Sprinkling Chinese Herbal Medicine: On rural hillsides, beside streams, and along roadsides, there are many Chinese herbal medicines, such as pine needles, camphor leaves, hemp willow leaves, Chinaberry, Acorus calamus, and gallnut. When dead fish float on the surface of the fish pond, when fish suddenly stop feeding for reasons other than weather, or when fish swim alone away from the group, the above Chinese herbal medicines can be collected, or collected regularly, at 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 both the decoction and water into the pond. After 12 hours, the water color turns brown. It is non-toxic and harmless to fish and water quality, and will quickly control the possible spread of potential fish diseases or prevent the occurrence of fish diseases.

Ecological Disease Prevention: In practice, it has been found that in the fish pond ecosystem, if the biological species are more numerous and complex, the ecosystem is more sound, and the disease resistance of the system is stronger. If fewer 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, turtle, eel, as well as unavoidable wild miscellaneous 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 "catfish effect," carp and crucian carp search for food and dig at the pond bottom, destroying the environment where pathogens easily breed. Diseased fish, because of their sluggish movement, are eaten by carnivorous fish, cutting off the transmission route of pathogens. The ecosystem automatically prevents disease, so the pond disease incidence rate is low.

Toads Preventing Fish Disease: After many years of observation, where 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 where the toads are not likely to escape, toads can be caught directly and put in. In fish ponds where they are likely to escape, use bamboo baskets or net bags to enclose them before putting them in; the location is better at the water inlet, at more than 5 toads per mu per pond. It is best to release the enclosed toads after 3 days to avoid death. Toads are more common in towns and cities by riversides where plants are lush, and can be found at night with a flashlight. Their escape 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 naturally can effectively prevent the occurrence of fish pond diseases.