Photos Detail Why Pet Goldfish Shouldn’t Be Dumped in a River

August 17, 2016 Updated: November 13, 2017

Goldfish, when dumped into a river or a lake, have the potential to be massive pests, according to new research.

Scientists at the Centre of Fish and Fisheries at Murdoch University in Australia have been attempting to control goldfish in the Vasse River, in the southwestern portion of Western Australia. They’ve recorded “alien” goldfish traveling long distances to disrupt natural ecosystems in the state, becoming huge in the process.

“Once established, self-sustaining populations of alien freshwater fishes often thrive and can spread into new regions, which is having a fundamental ecological impact and are major drivers of the decline of aquatic fauna,” lead author Dr. Stephen Beatty said in a news release.

He added that their research found that the goldfish “displayed a significant seasonal shift in habitats during breeding season, with one fish moving over 230 kilometres [142 miles] during the year.”

Goldfish are native to east Asia. Because of their popularity as pets, they’re now considered among the world’s most egregious invasive aquatic species, the researchers noted. “Once the fish become established, their eradication is often difficult, which is having a significant impact on Australian ecosystems,” the press release stated.

They can potentially introduce diseases, disturb habitats, and also compete with native species of fish, Beatty said.