Ginormous goldfish are invading Australian rivers A man holds one of the giant goldfish. (Murdoch University/AP Photo/Martin Mejia)
Ginormous goldfish are invading Australian rivers
Lexile

There's nothing cuter than a goldfish. They are small, bright and distinctly cheerful-looking. They're a staple of fish tanks around the world. But Australian scientists are not so enamored with the little darlings, reports Johnny Lieu for Mashable. Not only are they invading Australian rivers, but they're also growing to gargantuan sizes.
 
The huge goldfish of Western Australia are anything but adorable. Over the last 15 years, Lieu reports, they've taken to freshwater rivers in ever-greater number along with a host of other aquarium fish. A new study has been published in the journal Ecology of Freshwater Fish. Researchers reveal how the fish have spread throughout Australian waterways. The fish have grown ever larger as they go.
 
The fish are not just big, the study found, they're incredibly mobile. In just five days, they can travel an average of one mile in the river. One fish went a whopping 3.35 miles in a mere 24 hours.
 
Over a year-long period, researchers tracked the movements of goldfish in the lower Vasse River. The researchers used acoustic testing and tagging to determine what fish were doing. The goldfish that were studied didn't just swim around. They appear to have spawned. Ecologists call it "spawning migration," a pattern in which fish breed in areas far away from their normal hangouts.

That's bad news. This is according to Stephen Beatty. He is a senior research fellow at Murdoch University's Centre for Fish & Fisheries Research, who led the study. He spoke with Smithsonian.com.
 
"The fact that they're so big is really symptomatic of the other impacts in the river," Beatty says. The river, he explains, is warm and stagnant. Those are perfect conditions for pet goldfish, who make their way into waterways after being released by their owners.
 
"The goldfish have really capitalized on that," he says. Not only do the goldfish disturb the habitat and potentially consume invertebrates and fish eggs, his team suspects that they are also disease vectors.
 
Carassius auratus originated in Asia. That is the scientific name for goldfish. They are kept as pets the world over. But when they're released into the wild, the well-behaved fish tank friend becomes a foe to other wildlife. Not only do they grow without the constraints of a tank and commercial fish food, but their feeding frenzy also causes mud and debris to rise from the bottom of the river. That fuels the growth of aquatic plants, which can degrade the river even further.
 
And while splashing around in the warm, nutrient-rich environment they love, they breed like crazy.
 
It's become an issue throughout the world.  A Boulder, Colorado, lake teems with the fish and in Alberta, Canada, the problem has become so bad that officials pleaded with the public not to release them.
 
For Beatty, all that press is a good thing: "They're a bit of a flagship because they do get that media attention," he concedes. But their star status has a downside - a misconception that if your goldfish is tiny, it won't hurt to drop it in a lake or river.
 
"Introduced species can have really unpredictable impacts, even cute and fuzzy ones," he says. "Please don't release anything into rivers or wetlands that are not native there."

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CRITICAL THINKING QUESTION
How do the goldfish interfere with the existing habitat?
Write your answers in the comments section below


COMMENTS (175)
  • sams-pav
    9/14/2016 - 09:52 a.m.

    I guess this is better than the Emu Wars! Hope they don't lose this one. lol.

  • matth-pav
    9/14/2016 - 09:59 a.m.

    i wish that i had a goldfish that big. i would put in a fish tank and feed it worms.

  • samanthas-1-ste
    9/14/2016 - 11:05 a.m.

    The goldfish are eating the small invertebrates and fish eggs. They are also bringing in a lot of disease as well. People should really stop releasing these fish into there or else the already existing problem could become a lot worse in the future.

  • tiffanyh-ste
    9/14/2016 - 11:51 a.m.

    Goldfish can grow really fast so the more room they have the bigger they're going to get.

  • hansiddhs-eat
    9/14/2016 - 11:54 a.m.

    Introduced species can have really unpredictable impacts, even cute and fuzzy ones.If goldfish are not in their natural habitat they could destroy the habitat.That is sad.Especially for the goldfish because they chose to invade Australia


  • joeg-orv
    9/14/2016 - 12:10 p.m.

    All of the animals that live in the habitat will be unfamiliar with the new type o fish and they wont know what to do with it. Do they eat it, does it eat them, will they eat the other animals food? They could very well change the habitat of other animals.

  • hayleel-ste
    9/14/2016 - 01:46 p.m.

    The huge goldfish could have very unpredictable impacts, they could do something to the habitat that was completely unpredictable. Goldfish may be cute and colorful but living in a different environment then usual could lead to a disaster then leading to a huge conflict that may or may not be able to be solved.

  • christophero-har
    9/14/2016 - 02:42 p.m.

    The Goldfish interfere with the existing habitats by causing harm to invertebrates and fish eggs by consuming them.They can also carry many diseases which most wild river fish are not prone to. On top of this they breed like crazy in the river water they are found in which just doubles the danger. I hope they can resolve this issue with balancing out the problems with wild goldfish with more solutions.

  • draikep-har
    9/14/2016 - 02:46 p.m.

    Goldfish interfere with our existing habitat because their food creates mud which floats up and fertilize the algae and that stuff. They also can eat other fishes eggs which could lead to extinction. They might bring a disease which might defeat all the other fish. Goldfish might eat all the food for the other fish which could also cause extinction. It could lure all the other fish that we don’t want because the other fish might want to eat the goldfish.

  • senem-eat
    9/14/2016 - 06:06 p.m.

    They breed at a very high rate which causes many problems such as. Driving away the native species and carrying harmful diseases.

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