Thousands of mosquito-eating fish have been released into parks in Foshan, Guangdong province, to help prevent and control the spread of dengue fever, chikungunya, and related diseases transmitted through mosquitoes.

Foshan is being hit hardest by chikungunya, with more than 4,000 reported cases in the city, about 20 kilometers away from Guangzhou, the Guangdong provincial capital.

Zhang Huabin, deputy director of Foshan's Chancheng district urban management and comprehensive law enforcement bureau, said it is Foshan's first attempt to release the Gambusia affinis species to reduce the mosquito breeding density and cut off the transmission chain of mosquito-borne infectious diseases.

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"The fish fries feed on mosquito eggs and larvae, which helps to eliminate mosquito eggs and larvae in the water," he said.

According to statistics, a larvivorous fish fry can eat between 100 and 200 mosquito larvae every day.

Monitoring from the district's urban management department has shown that after the release of mosquito-eating fish, the density of mosquito larvae in the water is expected to decrease by more than 60 percent within three months.

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Although the effects of mosquito-eating fish take longer to manifest, the strategy is pollution-free, environmentally friendly, and sustainable compared to traditional chemical disinfection and sterilization methods, authorities said.