Have you ever considered disposing of unwanted goldfish by releasing them into the nearest waterway? It might seem the kindest thing to do, but scientists have found they turn into monsters that choke the waterways and threaten the well-being of native fish.
Officials in Burnsville, Minnesota, in the United States this week tweeted images of several football-sized goldfish that had been pulled out of a local lake.
It happens in Australia, too, with researchers from the school of Veterinary and Life Sciences at Perth’s Murdoch University reporting that they regularly find goldfish that weigh over 1kg, with one tipping the scales at 1.9kg.
It turns out that, when released into the wild, these fish have the ability to grow and wreak havoc on the ecosystem.
Like their common carp relatives, goldfish feed at the bottom of lakes, where they uproot plants and stir up sediment, which in turn damages the water’s quality and can lead to algal blooms, harming other species.
Even worse, the goldfish eat other fish’s eggs and can spread disease.
People with unwanted fish in tanks at home are advised to either return them to a pet shop or humanely euthanase them by putting them in the freezer.
Image: City of Burnsville