Gigantic Goldfish

DR. STEPHEN BEATTY/MURDOCH UNIVERSITY

BIG FISH: Most pet goldfish weigh just a few ounces, but this fish pulled from a river weighed more than 4 pounds.

When some goldfish owners no longer want their pets, they dump the fish into local waterways. In a tank, the fish stay relatively small. But in the wild, goldfish can grow to enormous sizes. This summer, officials removed dozens of massive goldfish from a lake near Burnsville, Minnesota— some were more than 38 centimeters (15 inches) long!

FRANCIS WIBISONO/ALAMY STOCK PHOTO

POPULAR PET: About 11.5 million households in the U.S. have pet freshwater fish such as goldfish.

Goldfish are native to China and East Asia. In many places across the U.S., they have become an invasive species. These non-native organisms can harm the local ecosystem—a community of organisms interacting with their environment. With that in mind, “only buy a new pet fish if you’re sure you want to keep it,” says Chelsey Blanke, a researcher at the Minnesota Department of Natural Resources.

Back to top
Skills Sheets (2)
Skills Sheets (2)
Lesson Plan (1)