Uh-Oh. Your Childhood Pet Is Threatening Lake Tahoe

‘Monster goldfish’ are breeding in the lake and threatening its ecosystem.
One of Lake Tahoe's newest inhabitants: the monster goldfish. (Photo: Heather Segale/LiveScience)
Feb 24, 2013· 2 MIN READ
A Bay Area native, Andri Antoniades has previously worked as a fashion industry journalist and a medical writer.

Poor goldfish—they often live out their short lives in tiny bowls, a “runner-up” pet for generations of small children who really would have preferred a dog. But in a strange twist of what may be karmic retribution, giant-sized goldfish have recently infiltrated California’s Lake Tahoe. And they’re not only eating everything in sight; they’re beginning to pose a threat to the health of the lake’s ecosystem.

The Associated Press reports that researchers from the University of Nevada are finding monster goldfish in increasing numbers in Lake Tahoe’s icy waters. How they’re surviving in such cold temperatures remains a mystery, but given their unusual size, they seem to be thriving. While most goldfish are about two inches long, the jumbo-sized goldfish in Lake Tahoe measure about a foot-and-a-half—and according to researchers, they’re breeding.

Where did the fish come from? From us. They’re cast-off pets. Known as aquarium-dumping, owners who can’t or don’t want to continue taking care of their fish often dump them into nearby lakes and streams, thinking they’re doing the fish a favor by setting them free. But introducing new species to old ecosystems can be a recipe for disaster. Just ask Florida. Or Guam.

Conservationists are particularly concerned because Lake Tahoe is known for its crystal-clear waters, and its monster goldfish are a threat to it. Researcher Sudeep Chandra told KCRA-TV that these giant fish consume quite a bit, causing them to excrete an excessive amount of nutrients, which in turn stimulates algae growth.

While the giant goldfish of Lake Tahoe are not the biggest invasive species that live in the lake—that distinction goes to the large-mouth bass—Chandra stated that “even a small creature can have a big impact if there are enough of them.” Considering how quickly these fish are spawning, that’s a definite concern.

Surprisingly, the problem isn’t unique to Lake Tahoe. Aquarium dumping has produced monster goldfish in other states, as well as in the U.K. and France. According to one study reported on in LiveScience, the aquarium trade has contributed a third of the world’s worst aquatic and invasive species.

It’s a problem the state of Florida knows well. Once prized as exotic pets, Floridians who owned Burmese pythons started letting them loose in the Everglades once the snakes became too large and dangerous to house. Not understanding the implications of their actions, many probably thought they were compassionately setting their snakes free. But today, those Burmese pythons have decimated much of the Everglades’ indigenous animal populations, and the state is so desperate to contain the problem, it went so far as to encourage its own citizens to kill the beasts themselves.

While Lake Tahoe’s problem certainly hasn’t reached the level of Florida’s, researchers are urging residents to stop aquarium dumping. For those who currently own fish and perhaps would like not to anymore, LiveScience recommends that instead of dumping them—or flushing them—owners contact the original pet store where they were purchased, or their state’s department of fish and wildlife.

A Bay Area native, Andri Antoniades previously worked as a fashion industry journalist and medical writer. In addition to reporting the weekend news on TakePart, she volunteers as a webeditor for locally-based nonprofits and works as a freelance feature writer for TimeOutLA.com. Email Andri | @andritweets | TakePart.com