Scientists Concerned about ‘Monster’ Goldfish Pulled from Lake Tahoe Waters : The World We Share

Scotland has their feared but beloved Loch Ness monster. The Pacific Northwest has Bigfoot. Lake Tahoe now has its own “monster.” If not dealt with, these “monsters” could destroy the lake’s entire ecosystem.

Tahoe’s “monsters,” aka goldfish, were found during a recent survey of the area. The first to be found, a goldfish that was nearly 1.5 feet long and 4.2 pounds in weight, was only one of about 15 other goldfish.

“During these surveys, we’ve found a nice corner where there’s about 15 other goldfish,” environmental scientist Sudeep Chandra of the University of Nevada, Reno, told Live Science. “It’s an indication that they were schooling and spawning.”

While it may seem strange to call goldfish monsters, these infamous house pets are considered an invasive species of warm-water fish. They excrete unique nutrients that result in algal blooms, which would could murk up the clear, pristine waters of Tahoe. What’s more, they can devour the lake’s native species.

“The invasion is resulting in the consumption of native species,” Chandra said.

But goldfish aren’t the only invasive species threatening natural waters like Lake Tahoe; Chandra says that everything from tropical fish to seaweed and snails have been pulled out of the waters all over the U.S., as well as waters in other parts of the world. An algae plant known as Caulepra, which produces a toxic compound that kills fish, was eradicated from the lagoons in Southern California back in 2000. While the cost of removing the plant was astronomical, the environmental costs of not removing the plant would have been devastating.

So where are all these invasive fish and plant species coming from? Some have made it into the natural ecosystem through live seafood, fish owners dumping their fish, live bait and fishing and recreation vessels. But a recent report on California’s aquarium trade found that the biggest contributor to the problem is aquarium dumping. Williams, the lead author of the report, told OurAmazingPlanet, a sister site of Live Science, that though it is not known how many aquarium owners are dumping their fish, a survey of aquarium owners in Texas showed that at least 69 percent of fish keepers admitted to dumping.

“Globally, the aquarium trade has contributed a third of the world’s worst aquatic and invasive species,” Williams told OurAmazingPlanet.

So how big is the problem, exactly? Williams said that, in sea ports in San Francisco and Los Angeles alone, there are more than 11 million non-native marine organisms representing at least 102 species. Thankfully, Williams says that the problem can be fixed, at least to some extent.

“It’s pretty simple: Don’t dump your fish,” she said.

Instead, Williams suggested that fish owners call the pet shop that sold them the fish or the state department of fish and wildlife. Even euthanasia can be used to dispose of unwanted fish. Pet fish owners should be aware, however, that flushing fish down a toilet can be a problem for both the fish and the pet owner’s plumbing. Another option not mentioned by Williams could include rehoming the fish to someone that is more able or willing to care for larger or more aggressive fish species.