Freed goldfish put biodiversity at risk

Pet goldfish released into the wild are wreaking havoc on native species, research has found.

Once out of the aquarium tank and let loose in open waters, they can turn into fat, 2ft long “giants”. They gorge on insects and tadpoles – outcompeting rivals and threatening biodiversity.

Dr James Dickey, the report’s lead author of Queen’s University Belfast, said: “Our research suggests goldfish pose a triple threat. Not only are they readily available, but they combine insatiable appetites with bold behaviour. They could pose a real threat to native biodiversity in rivers and lakes, eating up the resources that other species depend on.”

The findings in the journal Neobiota follow appeals to aquarium owners in Minnesota to stop releasing pets into waterways after several large goldfish were pulled from a lake. As many as 50,000 goldfish were removed from local waters in nearby Carver County.