Photo Shows Why Pet Goldfish Shouldn’t Be Dumped in a River

April 23, 2019 Updated: October 10, 2019

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.

A goldfish found in a waterway (USGS)

“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.


In a New York Times article in 2016, “Goldfish are one of the world’s worst invasive aquatic species, with outbreaks also having been reported in Nevada, Colorado and Alberta, Canada, in the last several years.”

According to the report, the fish in the Vasse River “have the fastest known growth rate of goldfish in the world,” said Stephen Beatty, a researcher at Murdoch University.

He added: “Once you introduce something into a new environment — even if it’s a cute, cuddly aquarium fish — it can have quite unexpected, serious biological consequences.”

The goldfish is a type of domesticated carp and was first bred in ancient China.

“For centuries, goldfish were prized symbols of luck and fortune. Shortly after they made their way to the United States in the mid-1800s, however, they transitioned from the exotic to the mundane,” the report detailed.

“The United States government played a large role in this, according to Katrina Gulliver, a historian who has chronicled the goldfish. For decades in the late 1800s, the newly established Commission on Fisheries gave goldfish to Washington, D.C., residents as a publicity stunt, handing out as many as 20,000 fish in some years.”