Goldfish Gone Wild

Zoom In
CREDIT: Jim McMahon

Most goldfish weigh just a few ounces. This one, found recently in a river in Australia, tipped the scales at more than 4 pounds. Fish like this are part of a growing problem: People who no longer want their goldfish release them into streams and lakes, where the fish have no natural predators. Outside their fishbowls, they become an invasive species: non-native organisms that harm local plants and animals. A recent Australian study found that once in the wild, goldfish can grow to more than a foot long, gobbling up natural food supplies and spreading disease to native fish. And it’s not just a problem in Australia; goldfish invasions have also been reported in North American waters in the past few years. Ecologist David Morgan, who worked on the study, has advice for owners of unwanted goldfish: “Return them to the pet store.”

CREDIT: Dr. Stephen Beatty/Murdoch University (goldfish)

Want to See More?

Subscribe to Upfront for full access to articles, lesson plans, skills sheets, videos, cartoons, and other resources.

Already a subscriber?