Giant Goldfish Hybrid As Heavy As A 10-Year-Old Is A Reminder Not To Dump Your Pets

Mr Bubbles can grow to an enormous size out in the wild, and he's gonna be mad when he finds out what you did.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

how big do goldfish get
This puny specimen was half the weight of The Carrot recently caught in France. Image credit: KoiQuestion, via Flickr

A record-breaking goldfish has been caught in Champagne, France, where an angler dragged a 30-kilogram (67-pound) specimen from BlueWater Lakes. The carp fishery released the behemoth, known as The Carrot, 20 years ago and it has since grown to be one of the largest in the world.

There are many breeds of goldfish, but as a general rule, they are hardy, golden types of domesticated carp. They come in all kinds of curious arrangements, like the celestial eye goldfish, and are sometimes hybridized with other fish like koi, as was the case for The Carrot.


The Carrot’s carp-koi hybrid status meant that given 20 years to roam, she has grown to over 30 kilograms in weight, which is about the same as the average 10-year-old child. It took Andy Hackett from Worcestershire, UK, 25 minutes to reel her in before snapping a few photos and letting her go.

How do goldfish get so big?

The enormous size of The Carrot serves as a reminder not to release your pets into the wild, because as hardy fish, certain types of goldfish can grow to enormous sizes. Gigantic goldfish have been reported as a problem in parts of America where they upset the silt bed and rip up plants, and authorities believe pet owners are partly to blame.

Goldfish dumped into wild waterways represent an invasive species and can even muscle-out native species by outcompeting them for resources. Getting so swoll requires a voracious appetite, and in the process, they can pick up and pass on parasites.

Goldfish are generalist feeders who will eat whatever’s on offer, and depending on the breed, they can live for a surprisingly long time. Long-lived breeds can grow to a foot or beyond, and if they’ve been hybridized with another fish, like The Carrot, they can go even bigger.

How big do goldfish get?

The reason we associate goldfish with being mini, bowl-dwelling animals is that to an extent their size is dictated by their environment. A fish kept in a small tank on modest feed will stay small, partly due to stress, and will stay that way until they die.

However, if you upgrade that same goldfish to a big tank with lots of food, it’ll quickly blossom into a much bigger fish.

It’s illegal in the US to dump unwanted pets into wild waterways, but the US Fish and Wildlife Service have tips on breaking up with Mr Bubbles if you really need to part ways. And you'll want to stay on his good side considering goldfish are driving cars now.


  • tag
  • fish,

  • animals,

  • Pets,

  • hybridization,

  • invasive species,

  • goldfish,

  • fishing