Releasing animals into the wild as benevolent act, which is a long-held tradition in the country and popular in Guangdong province, may disturb the public and harm ecological balance if not conducted scientifically, an expert said.
"It is not about releasing animals into the wild wishfully and unconditionally but with consideration of the safety of both the people practicing it and those living at the sites of such activities," said Zhang Jiansheng, executive deputy president of the Guangdong Fangsheng Association.
If such activities disturb the public, it is counter to the benevolent and caring intent, he said.
The remarks came after a widely forwarded micro blog post about a woman who freed poisonous snakes, causing worry and criticism earlier this month.
Some posters thought a park in Shenzhen was the site where the snakes were freed though a police investigation indicated it was a mountain in a village in Yingde, another city in Guangdong.
Those freeing animals should study the local ecological environment and only release species that would help maintain ecological balance and avoid harm to both the animals freed and the local species, Zhang said.
"If alien species are freed, biodiversity will be reduced, which will lead to an ecological imbalance or disease and harm other species and people. Massive invasions of alien species will destroy the fragile ecological environment," Zhang said.
Suckermouthed catfish have been introduced to the Pearl River and Xijiang, Beijiang and Jianjiang rivers in Guangdong, in which they are alien, according to the Pearl River Fisheries Research Institute of Chinese Academy of Fishery Sciences.
People fishing along the Guangzhou section of the Pearl River can often be seen catching the species.
Ponds used to release water creatures at scenic spots in Guangdong now hold a large population of red-eared slider turtles, another alien species.
Both species are sold at pet markets in Guangzhou.
American bullfrogs have been released by some people at Olympic Forest Park in Beijing and local frogs are rarely seen now, Beijing Daily reported earlier this month.
Guangdong is the province with the most non-native species in the country, recording 150 such species in 2008, a situation that stems from the habit of releasing animals for spiritual belief or animal protection, said Gong Shiping, a researcher with the Guangdong Entomological Institute and South China Institute of Endangered Animals.