Goldfish are commonly purchased as pets or fishing bait, but they become an invasive species if released into local lakes.
A recent study from the University of Missouri found that goldfish, a species of fish native to Asia, disrupts local ecosystems because they grow in size and outcompete other organisms.
Dr. Rick Relyea is the co-author of the study and director of the Johnny Morris Institute of Fisheries, Wetlands, and Aquatic Systems at the University of Missouri. He said the best way to reduce environmental harm is to prevent goldfish from entering the ecosystem to begin with.
“It’s really almost impossible to get any invasive species out of a lake, because they can typically make a lot of offspring,” Relyea said. “It's a very very difficult thing, so it's always better to not have them get in than try to remove them once they are.”
Relyea said pet owners should return unwanted goldfish to the pet store instead of releasing them.
Andrew Branson is a fisheries programs specialist from the Missouri Department of Conservation, and he said pet and bait goldfish should not be released into the wild.
“Goldfish are allowed to be used as bait because they’re on the approved aquatic species list, but they’re not allowed to just be dumped in the water,” Branson said. “So, we don’t want fishermen dumping their leftover bait, and we don't want people with aquariums dumping their aquariums.”
Branson said any leftover bait goldfish should be taken home. They can also be safely euthanized if placed in ice-cold water, he said, and can be used as compost or fertilizer.
