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Super-Sized Goldfish Pose Giant Problem for Lake Tahoe

Brianne O’Rourke, with the California Department of Fish and Wildlife, holds a large goldfish found in the Tahoe Keys of Lake Tahoe. (Photo courtesy of the California Department of Fish and Wildlife)

Brianne O’Rourke, with the California Department of Fish and Wildlife, holds a large goldfish found in the Tahoe Keys of Lake Tahoe. (Photo courtesy of the California Department of Fish and Wildlife)

Lake Tahoe, the country’s highest alpine lake, is no goldfish bowl.

But U.S. Forest Service fish biologists with the Lake Tahoe Basin Management Unit said they’re well-acquainted with the big goldfish – several pounds and up to 4 to 8 inches long – living in the large freshwater lake along the border between California and Nevada.

The warm-water fish recently made the news when University of Nevada researchers displayed photos of an enormous goldfish found in Lake Tahoe. While the goldfish may seem innocent and beautiful in a glass fish bowl, they like other invasive species can wreak havoc on the lake’s natural ecosystem.

Invasive species can harm native fish by destroying their habitat, preying on them directly or interfering with their food source. In the case of the giant goldfish, researchers believe they may actually be harming lake clarity by fueling algae growth with their waste. When biologists find warm water fish during surveys, they remove them.

Forest Service biologists have surveyed streams in the Lake Tahoe Basin since 2007 looking at numbers of native fish versus invasive species. They found that nonnative species such as brook trout, rainbow trout, blue gill and brown bullhead accounted for more than half of the fish surveyed.

“We’re already seeing some of these invasive species move upstream, but we’re expecting the expansion to greatly increase if we don’t continue and even increase control efforts in Lake Tahoe’s near-shore environment,” said aquatic biologist Maura Santora.

Climate change plays a role in that potential increase.

“As Lake Tahoe’s waters warm, invasive species can more easily breed in the near shore and travel to other parts of the lake,” said Sarah Muskopf, a fish biologist with the agency. “We’re most concerned about marinas, canals and wetlands that are closely connected to Lake Tahoe.”

Lake Tahoe Basin Management Unit staff work with a multitude of partners, including the California Department of Fish and Wildlife, the University of Nevada at Reno, and the Tahoe Regional Planning Agency, to complete the surveys and on other invasive species prevention, control and eradication efforts.

However, it’s the public that may have the greatest role to play in stopping this threat.

“We believe that these goldfish were originally introduced to Lake Tahoe by well-intentioned pet owners,” said Santora. “If we can persuade the public not to release their aquarium fish or leftover bait fish into the lake, we will have made a critical step in addressing the problem of invasive species.”

And for the record, the largest goldfish on record, according to Guinness World Records, was recorded in 2003 as being 18.7 inches from snout to tail-fin. The weight was not provided.

Forest Service crews survey fish species in Lake Tahoe Basin streams. Data shows that invasive species now outnumber native fish. (Maura Santora/U.S. Forest Service)

Forest Service crews survey fish species in Lake Tahoe Basin streams. Data shows that invasive species now outnumber native fish. (Maura Santora/U.S. Forest Service)

14 Responses to “Super-Sized Goldfish Pose Giant Problem for Lake Tahoe”

  1. Eric Mills says:

    I wonder how many of these non-native goldfish originate as “prizes” at our State and County Fairs?

    There should be a ban on this practice: bad for the fish, bad for the environment.

  2. Ken Asmus says:

    Gold fish have been found in many ponds and streams in Michigan, however in the ponds where they are released, they cannot breed for some reason. I have seen this many times as the ponds around college campus’s are often full of mature fish but no fry or hybrids with other carp. Do these fish reproduce?

  3. Meghan says:

    If the largest goldfish ever recorded was 18.7 inches long, how is the woman in the photo holding one that looks to be larger than that? And if the ones in Lake Tahoe are “up to” 4 to 8 inches long (which is not very large for a full-grown goldfish) shouldn’t they actually be “up to” whatever the length is for the fish in the photo?

    Something’s fishy here!

  4. Maura Santora says:

    Thanks for the interest:) Replying…

    Ken, we aren’t sure if they are reproducing. Small size classes have not been documented in the lake, though a few gravid females have been caught.

    Meghan, there is some editing in the blog, so to clear up… I don’t know what the size of fish is in the picture (it’s not FS work) but I suppose the fish could have broken the record of 18.7 inches??. The “up to 8 inches” was what we have found in our STREAM surveys, previous to this news release of what researchers have found in the LAKE surveys. I agree, it is a bit confusing the way it got written up.

    Correction – under the photo of my FS crew working I was misquoted. It should say “…Data shows that NON-NATIVE species now outnumber native fish.” The Lake Tahoe Basin is dominated by non-native trout species which were intentionally introduced and are currently managed by state agencies. Invasive speceis are not managed and were not intentionally introduced, therefore they have invaded. Invasive fish make up a very small percent of total fish in Lake Tahoe (thouh in certain locations they are likely outnumbering other fish).

  5. James Wolford says:

    Also wondered about the length (new world record???). Cannot find an official (or unofficial) story from CDF&G…anyone know if one exists??? I live in Tahoe City so am quite curious.

  6. Gianni says:

    We dive in tahoe all the time and are wondering where we might be able to see these goldfish and get some pictures. Is there a beach we can get to them from or are they actually in the marina keys development?
    Thank you, We are so looking forward to seeing them.

  7. Terri says:

    This fish in the pic, looks like a koi, or koi carp, as some people say… Judging by the scales.
    I concur about not using these animals as prizes. They, however, should NOT be kept in bowls.
    People that release any animal they don’t want anymore are…. Idiots, remember the snake heads released here in Maryland. People need to think! Good luck with the Goldie’s, too bad they can’t be caught and put into ponds where they would be appreciated.

  8. korin says:

    We introduced gold carp as food for the giant 100ft big mack trout. There were thousands of them over 40ft and nothing to eat but their own young. So why are there no pics of them?

  9. Jerome says:

    “The Lake Tahoe Basin is dominated by non-native trout species which were intentionally introduced and are currently managed by state agencies. Invasive species are not managed and were not intentionally introduced, therefore they have invaded.”

    I don’t know how you think something that is living where it was born could be “non-native”. Where exactly would those trout have to go to be “native”?

  10. Anthony says:

    Respectfully, Cheva, three points.
    #1. Any kid with an aquarium could tell you that gold fish do not need warm water to thrive.
    #2 In certain parts of the country, you can not keep Koi or Goldfish even in a suburban pond without it being enclosed, otherwise birds of prey will pick it 100% clean. Goldfish are biologically disadvantaged to survive in the wild as they are incredibly easy to be seen from above.
    #3 Could this be more a factor than Climate Change? How many birds of prey are killed by windmills? The answer, are willing to admit.

  11. jic says:

    Since when have goldfish been “warm-water fish”?

  12. nobody in particular says:

    They’re just trying to make a better life for their families! Why are you prejudiced against non-natives? Why do you hate diversity? You should know that’s racist, and you should really think about what you’re saying because some people might be offended.

    P.S. We don’t call them invasive species anymore. The new term is ‘unprecedented friends’.

  13. john zeggert jr says:

    I think you guys should Look in doing what other states have done like LOOk at put hybread tiger muskies or wall eyes or regular Muskies in there.

    i m pretty sure they would clean the gold fish out they will eat any thing so there your answer.

  14. john zeggert jr says:

    guys serriously Muskies and tiger muskies put them in there they will clean out the gold fish issue problem solved

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