Seething with tropical fish: The selfishness of people flows in “Guppy Stream”

Baby guppies, a tropical fish, swim in Jukdangcheon in Icheon-si, Gyeonggi on November 20. Kim Tae-hui

Jukdangcheon stream near Bubal Station in Icheon-si, Gyeonggi is an attraction known nationwide, but at first glance, there doesn’t seem to be anything special there. The stream flows in the middle of nowhere, so there’s nothing much to see or anything special to enjoy.

Despite such conditions, Jukdangcheon stream is famous enough to attract people from all over the country because of the water temperature of the stream and the fish species that inhabit it. Near the stream, there is a large semiconductor factory. The factory uses water as a coolant in the memory manufacturing process and purifies and releases the water into Jukdangcheon. This keeps the water temperature of the stream somewhere around 20°C even in the winter.

Someone abandoned guppies, a tropical fish, into this Jukdangcheon, where warm water flows all year round, and the guppies came to settle in the stream. It’s unclear as to when guppies first began to inhabit the stream. But stories about seeing guppies in Jukdangcheon began spreading online in 2018. Due to the guppies that settled in the stream, Jukdangcheon is now better known as Guppy-cheon or Guppy Stream than its original name.

When the Kyunghyang Shinmun visited Jukdangcheon on the morning of November 20, one could easily find guppies in the stream. They were mostly found under water plants where the water flowed slowly. You could see fully grown guppies with colorful tails to fry smaller than a grain of rice. By the stream, there was also a net that someone had left behind. Monday was cold with temperatures reaching as low as 0°C, but when we touched the water, it was as warm as that in a home aquarium.

In the past, Jukdangcheon was simply regarded as a mysterious place where tropical fish lived. Guppies were identified as a fish species that hardly had any negative impact on the ecosystem. The area that guppies could inhabit was restricted to the upper stream where warm water was supplied, so there was little concern of the species spreading to other areas.

However, recently there are growing concerns about Jukdangcheong. There is a growing number of eye-witness statements claiming many more species besides the guppy live in Jukdangcheon. There was also a statement about witnessing alien species designated by the Ministry of Environment as potentially harmful.

On Naver cafes and YouTube, one can easily find posts claiming to have witnessed various tropical fish species in Jukdangcheon including the suckermouth catfish, known as the janitor fish, the giant sailfin molly, the cichlid and the platy.

The YouTube channel, TV Saengmuldogam (illustrated biology, @tv.saengdo) posted a video claiming to have discovered the marbled crayfish in Jukdangcheon recently. The marbled crayfish, which the environmental ministry designated as an alien species to watch out for, reproduces through parthenogenesis, so even a single crayfish could quickly reproduce and disturb the ecosystem. After Jukdangcheon became famous as a habitat for tropical fish, some people seem to think of the stream as a site for releasing tropical fish, leading to the latest phenomenon.

Experts point out the harmful effects that the warm water and the fish species inhabiting the stream have on our ecosystem. “The stream being warm enough for tropical fish to live in and alien fish species inhabiting the stream are already disturbances to the ecosystem,” said Song Mi-young, a senior research fellow at Gyeonggi Research Institute. She stressed, “This is clearly wrong.”

An official of Icheon-si said, “It’s hard to stop people from releasing fish into the stream if the species is not designated as an ecosystem-disturbing species in the River Act, so for now, we plan to guide the citizens by putting up signs banning the release of fish around Jukdangcheon.”