Why are there giant goldfish in the US?

Look at the size of that goldfish!

Something fishy is going on in a city in Minnesota, US, where huge goldfish have been found in local lakes!

The city of Burnsville has released images that show a huge goldfish that was caught when city workers were doing a survey of Keller Lake.

It's believed the oversized fish are the result of pet owners dumping their unwanted goldfish in the lakes.

When released into the wild, goldfish can grow to sizes much bigger than they do in domestic tanks, and this can create disruption to ecosystems in the lakes.

Goldfish kept as home pets should only grow to around 5cm

Goldfish that are kept in home aquariums are expected to grow to about 5cm in length, but if they are released into the wild, they can grow much bigger and become difficult to remove.

Once in public waters, the goldfish can reproduce rapidly and can become a dominating species, where they can contribute to poor water quality by disturbing sediment and uprooting plants.

Goldfish are classed as a regulated invasive species in Minnesota, so it is illegal for people to take their goldfish and release them into any water.

The Minnesota Department of Natural Resources said back in January: "A few goldfish might seem to some like a harmless addition to the local water body, but they're not.

"Goldfish are in the minnow family and can work their way through city stormwater ponds and into lakes and streams downstream with big impacts, by rapidly reproducing, surviving harsh winters, and feeding in and stirring up the bottom like their close relatives, the common carp."

The City of Burnsville has pleaded with its citizens to not release their unwanted goldfish into public waters.

Have you got any goldfish? Tell us their names in the comments section!

Wildlife officials have been dealing with a similar problem in nearby Carver County, where 50,000 goldfish were removed from a creek in October last year.

The removal was part of a three-year plan to study and manage the species, which have caused problems across the US.

And, the US isn't the only country to suffer from giant goldfish.

In 2017, Munich city council in Germany said shoals of goldfish were starving out all rivals in local ponds and lakes.

And, large goldfish have been found in the UK's wild waters as well. In 2010, a British teenager pulled a 5lb (2.2kg), 16in fish from a lake in Dorset!