“Monster” Goldfish Multiplying in Lake Tahoe: Freshwater Species of the Week

Giant goldfish have been found breeding in Lake Tahoe. Photo: University of Nevada, Reno

I’m posting Freshwater Species of the Week a day early because I just caught wind that biologists have discovered “monster” goldfish breeding in Lake Tahoe.

I visited Lake Tahoe a few winters ago, and can say with experience that it’s a stunning natural gem. Snow-capped peaks ring the crystal-clear blue water, which supports a diverse ecosystem.

The lake is a huge draw to tourists to the California-Nevada border. The region supports a booming ski industry, although locals told me it seems even busier in the summer, when city dwellers pour in to swim, boat, hike, and cycle, or just cool off in the serene waters.freshwater species of the week

To keep Lake Tahoe as pristine as possible, a team of biologists from the University of Nevada, Reno (where Water Currents’ own Zeb Hogan is based!) and California State Fish and Game patrol its waters throughout the year. They are monitoring invasive species like largemouth bass. The scientists use electric probes to stun fish, and then they scoop them up with their nets to count and examine them.

As KCRA in Sacramento reports, researcher Christine Ngai of the University of Nevada, Reno, said, “You can get 200 fish in one scoop.” (We reached out to Ngai and are hoping to speak with her.)

But hungry bass is not all that the scientists pull up. “You just see this bright golden orange thing starting to float up, and you’re like, what is that?

“Then you take your net and scoop it up, and it’s like, it’s a goldfish,” said Ngai.

Some of these non-native fish have reached almost a foot and a half long in the lake. And they seem to be multiplying, say the scientists. In one day, Ngai and her colleagues caught 15 in one small part of the lake.

How Did Goldfish Get There?

KCRA suggests that goldfish may have been released in the lake by well-meaning pet owners. A commenter on Huffington Post also noted that goldfish are often used as cheap bait for bass, so that seems to be another plausible intro point, if they wiggle off the hook, or if fishermen empty their bait buckets at the end of the day.

Ted Thayer of Tahoe Regional Planning Agency told KCRA, “Those small things people do can have a large impact, when you consider that it’s probably not just one person doing it.”

For now, goldfish aren’t thought to be as big a problem as the non-native bass, since they are outnumbered 100 to 1. But the fact that they are new arrivals, and are breeding, is pause for concern. The researchers also point out that goldfish can have big appetites, and they excrete a lot of nutrients, which can dirty that clear water and stimulate algae to grow.

Tahoe, like most of the world’s lakes, is already facing stresses, from pollution to climate change. Non-native species often can tip the balance to a radically different ecosystem.

goldfish caught in lake tahoe
Invasive species, not pets. Photo: University of Nevada, Reno
Invasive largemouth bass pulled from Lake Tahoe. Photo: University of Nevada, Reno
  • R T Whitson III

    Goldfish are a type of carp, essentially aquatic swine. They root in the muddy substrate at the bottom for food. This ejects large quantities of silt into the water. As they evolved to deal with the silt, it does not bother them. Other species however, cannot deal with the silt and their gills become filled with it, restricting their oxygen intake. Goldfish and other carp species have ruined many bodies of water for other species because of this. Carp were the first domesticated fish and are useful in rice paddies where their rooting helps to oxygenate the plant roots, and their waste nourishes the plants.

  • Chuck Sirron

    Those aren’t monster goldfish. Goldfish actually grow to that size if given enough space. They will only stay small if kept in a small bowl, where they eventually die because the bowl is too small. Since these are given a large habitat, they grow to their normal size.

  • Petr Jandacek

    When Capitalism thrived in America entrepreneurs would have seen this (and the Asian Carp) as and opportunity to get rich – harvesting and canning and selling gourmet carp to people who value such a resource. Among such gourmets are Asians,Czechs,Germans,Poles,Russians and Ashkenazi Jews who live or hail from these lands. Invite us to fish & chip-in & Bon Appetite!

  • GOD

    GOD Save The Universes

  • Michael Driver

    Yet another example of carelessness with our environment. People just willy-nilly dumping whatever into what will soon be a once beautiful lake. I assume that the Large Mouth Bass have been put in Lake Tahoe by “Sports Fishers” as has been done in many places in the name of sport! These ravenous fish will soon wipe out many of the native species. Too bad for us who enjoy nature for what it is, and not for sport, and entertainment! Too bad for our planet.

  • Ian Kirman

    Nice Shirt, Lake Tahoe Invasion Team Scientists

  • shirt admirer

    Yeah I’m not sure there is a Lake part of the
    Tahoe Invasive Team Scientists… And they might be all girls judging from that acronym…

  • Keith

    So the question is… How do they taste?

  • Michael Mitchell

    For monster goldfish problems stock with monster catfish.
    For monster catfish problem see above scientists.

  • rbockman

    gefilte fish

  • Coy Koi

    Don’t some keep these in koi ponds with some breeds going for lots of gold?

  • BellsW

    Believe it or not we had 4 huge goldfish here at one stage. We had to get another tank to separate them for more room. We believe it was the good quality food & plants we gave them to eat that made them grow so well. So if they are being found in large sizes in a lake, likely someone released unwanted ones & they have thrived on the plant life in the lake.

  • Andrew Allison

    Pathetic reporting! There’s nothing “monsterous” about these fish. Wikipedia reports that, “As of April 2008, the largest goldfish in the world was believed by the BBC to measure 19 inches (48 cm), and be living in the Netherlands.[20] At the time, a goldfish named “Goldie”, kept as a pet in a tank in Folkestone, England, was measured as 15 inches (38 cm) and over 2 pounds (0.91 kg), and named as the second largest in the world behind the Netherlands fish.[20] The secretary of the Federation of British Aquatic Societies (FBAS) stated of Goldie’s size that “I would think there are probably a few bigger goldfish that people don’t think of as record holders, perhaps in ornamental lakes”.[20] In July 2010, a goldfish measuring 16 inches (41 cm) and 5 pounds (2.3 kg) was caught in a pond in Poole, England, thought to have been abandoned there after outgrowing a tank.[21]” WHAT has happened to NGS?

    • Monstrous is a very subjective term. These fish may not be the world’s biggest goldfish anywhere, but they are pretty big considering that they are non-native to North America and are breeding.

  • Joy Matthews

    One of those goldfish is mine. I released a goldfish in the lake about 10 years ago. I thought that was a good thing to do.

  • Don

    I say we throw some Siamese Fighting Fish in the lake so they can around and kick some bass! Your bass and gold fish problem will be FINished!

  • Norrie

    The introduction of non-native species of any size invariably causes problems. It is, in my opinion, a wildlife crime to do so.

  • wayne wilkins

    I, lived in Lake Tahoe for 25 years. I, know that fishery there and I nuse to own the very first Fly Shop in the Lake area. Also used to work at The Outdoorsman Sporting goods store for years.
    The Bass have been in the Lake for many, many years. And only live in the shallow water where it’s warmer. They DO NOT get out into ANY of the main part of the Lake! As it’s too cold for them to survive! So, they are NO threat to the Trout population! 0 threat! Same for these Gold fish. But there are also Bluegill and Crappie in the Keys with the Bass. In fact there was a 5lb. Smallmouth Bass caught in the Keys back around 1999.
    There are NO Native species of Trout in Lake Tahoe, anywhere! All species of Trout and Salmon were planted there by the GOVT. and the Ca. Fish and game Dept. way back when!
    The Native species is the Lahotan Cutthroat Trout but they were wiped out by over fishing boy loggers to feed them.
    The U.S. Fish and Wildlife and Ca. Dept of Fish and Game and I did battle over their crap for several years!
    They try to say that the Bass would wipe out the Trout, which is a total LIE! Also another battle was over the Beaver there.
    After the burrowing Beaver was killed off for the felt industry, the Dam building Beaver was introduced to take their place from Colorado.
    The Dam builder was more of a benefit to the area than the burrower!!! With all the streams there, The dam builder catches ALL the silt and crap and each dam was a purifer!!! Which means a lot less silt ran into Lake Tahoe!
    Well the idiots from U.S. F.& W. and Ca. D. F.&G decided they didn’t want the non native beaver there and started killing them off! Steve Widowski wanted me to fish with him after I closed my shop. Steve is a Biologist with U.S. F. & W….
    So I showed up where he stated. He was already there and was knocking the snot out of Brook Trout. So I fished and when we finished, I stated to Steve, where are you fishing? He said a Beaver pond w/ a dam…… He then stated to me, well we’ll leave this one alone! Then the U.S. Forest Service pays some dudes half a million dollare to do a wetlands study!!!!! The Beaver created a wetland for nothing!
    So you got these mental midgets that think they have this great idea and RUIN things! If any species wasn’t MEANT to survive there, they wouldn’t!!!!!! The Brown Trout, Rainbow, Kokanee Salmon are ALL introduced into Lake Tahoe and there’s not one Lathontan Cutthroat….. So let them kill off all those species before they start on anything else!
    Don’t let tyourself fall for their B.S. about that Lake! As MAN is what’s ruining it, not the Bass, Goldfish, Dam building Beavers and Brown, Rainbow,Brook or Kokanee Salmon!
    I, know that Lake, I know that fishery, and I know about the beavers! Also know those that are spreading this crap are filling all with their B.S.
    Wayne M. Wilkins

  • Koizen

    HI is this an 8th grade forum? Judging from the replies I feel like I’m back in middle school..nice Shirt.. how about lets go with A Hominid Invasive Species Team, then this planet might have a chance. Gene pool definitely needs some educating… And thinning.

  • Koizen

    Thank you Wayne, Very well said… finally an educated opinion

  • David Rader

    Interesting comment, “wayne wilkins”! I’m glad my goldfish isn’t that big! I don’t have room for a bigger tank, so in the frying pan it would have to go! (since releasing it to the wild is apparently bad behavior, I must eat it, right?) hahahaha

  • Dmitry

    Happily, Russian winter freezes out all non-native creatures away. But I remember an occasion of seeing red-eared turtle in one of Moscow’s ponds. There were rumors about little crocodile swimming in Moscow river. I hope, it died in autumn.

  • M VH Denton

    Tahoe Invasion Team Scientists has men, too.

    Wayne Wilkins, while you have made good points about fish and game managers introducing various trout into Tahoe, the warm water game fish introduced illegally have begun to spread throughout the lake to other marinas. The nearshore water during the summer months is warm enough for those species to disperse. You’re right, Wayne, it has been human influence over the past from the extensive logging of the Tahoe Basin during the Comstock era, to development and inputs of effluent into Tahoe, to the dumping of goldfish in the Tahoe Keys, that is the threat to Tahoe. However, there are still native non-game fish like minnows who are threatened by the presence of the bass and blue gill. The clarity of Tahoe is negatively impacted by warm water fish through nutrient excretion. Like you, I know that Lake, I know that fishery – I grew up there, I do research there as a professional, and your comments are inaccurate and an insult to my colleagues and other professionals whose tireless efforts to restore Tahoe are worthy of recognition and respect.

  • Randall

    I’m surprised; I’ve never been there, but my understanding of Lake Tahoe is that it’s bloody deep and oligotrophic. I would not have expected goldfish to thrive…

    I guess at this point, the question is “Who cares?” Just give up. Eventually everything is going to be everywhere through human vectors. Eventually the native fish will get better at eating them, the system will l re-balance, and life’ll go on. It might take a thousand years, but life’ll go on well after humans have perished.

  • Michelle Bourassa Stahl

    How can non-native fish be a problem in a non-native (i.e. man-made) lake to begin with?

    • Hi. Lake Tahoe is not man-made, it is a natural alpine lake, thought to have formed about 2 million years ago.

  • cadillac kid

    More money needs to be spent on the study. We are talking GOLD fish. Much business to be had & do not forget about all the wild hoses. Spend more government money on these studies. The common dumb person like me needs to be educated by more studies. Bury the truth in more paper work.
    Chief Joseph says: VERY FEW WORDS ARE NEEDED TO SPEAK THE TRUTH. What about all the squaw fish (northern pike minnow) in the Columbia river.
    Decisions are made to make more money.

  • mikee70

    to Ms Ngai- concentrate on the goldfish first, leave the bass..for now. In this instance, you want as much predation on the goldfish fry as you can get. As you know, gold fish are in the minnow family and are essentially (by habit) carp. Carp fry will hide out in dense weed mass’s until they get to about nine inches. They essentially run out of invertibrate food, and are someswhat ‘displaced’ by the next seasons spawn, from there they move out as small schools into shallows looking for food.
    For a more effective control, I would suggest you find their preferred ‘hide out locations’ or: ( find where the adults are breeding in the spring…littoral shore line areas with a milfoil sp. or actually even emergent plant concentrations and shock after you detect egg mass’s stuck to the vegitation.) We shock when adults begin their spawning concentrations and get exuberant and don’t pay attention to the shocker boat ( they learn to recognize the sound of that particular motor and leave the area.
    Again, although bass are considered invasive to the system, they do have a ‘following’ but are very good preditors and as such, until you eliminate the gold fish and other cyprinids (almost an impossible task once they are present), consider the bass as your godfish removing partners !

  • M. O”Neill

    you have my last comment to MVH Denton

  • Merle Scoggins

    My grandfather had three gold fish, for many years, in at very large stock tank. Some of them weighed nearly 10 pounds. They never reproduced.

  • greg

    i hook bass that weigh anywhere from 4 to 12 pounds in the keys and the lagoon i release them GOOD LUCK TRY TO GET RID OFF THEM YOUR JUST WASTING THE TAX PAYERS MONEY find a job some where else and the gold fish are abundant in many colors i think the breed with the sun fish . i think this a amazing if you want to make Tahoe blue get rid of the keys BUT THAT WILL NEVER HAPPEN

  • greg


  • JRezzie

    just let the bass be theres all this hype talk bout how bass do this and bass do that,Bass are the APEX perdators of lakes.Of course there going to eat smaller fish like trout and possible gold fish.But the quiston is why are we evan worring about a gold fish who isnt native to lake tahoe when the Bass is native and has resided there for many years.It just seems silly to me to waste time and OUR TAX PAYER DOLLARS on a fish u can buy for 69 cents at a pet store

  • dexter

    exquistley correct sir!!!!!! As we all know the species of bass known as LARGEMOUTH are an extreme predator.To be exact the top apex predator nothing messes with these hefty shark of a fish.So lets learn to respect these majestic fish instead of down play them!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  • Brian Sweany


    These are researchers employed by the University of Nevada-Reno trying to make sure Lake Tahoe’s ecology isn’t damaged by an invasive alien species. They’re not fishermen posing with their trophies, and this has nothing to do with your taxes.

  • john zeggert Jr

    I think you guys should consider putting the Tiger hybread muskies or walleye like idaho n utah has in the lake tahoe that would get ride of the gold fish they will eat n thing i ve herd storys they will eat baby ducks and n thing really, put a giant tiger muskies in lake tahoe problem solved gold fish with in 2 yr s will be bye bye for good some of the muskies get up close to 60Lbs and very agressive

  • Vivian

    Some countries have problems feeding the poor. Some countries have too much food, they do not know what to do with it. Is this how we destroy the ecosystem when releasing pet fishes into the lakes? We have starving people. Can we feed them with these fishes?

  • T.J

    T.J needed a Giant Goldfish

  • Tahoe Winters

    Maybe the best solution is to get rid of the Tahoe Keys! These native marshlands were developed so a few hundred homeowners could have boat-up docks in their back yards. Of course that is not realistic nor is it possible to return Tahoe to the pristine state of pre-1880’s.

    As for introduced species… the rainbow trout, brown trout and mackinaw lake trout were also introduced to Lake Tahoe. These species are quite successful in the deeper waters across the entire lake and will never be eradicated. The true ‘native’ Lahontan Cutthroat Trout does not stand a chance against these aggressive invaders. The areas with minor reintroduction success of the Lahontan have only been possible with hatchery fish. At least the bass were making it on their own. More about fish and introduced species, check out pgs 4-5 at the UC Davis weblink.


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