Brilliant but deadly – don’t dump goldfish in rivers, pet owners said | Invasive species

If that locked goldfish starts to lose its luster, think twice before throwing it into the river or canal – the creatures may look innocent, but their voracious appetites, cold tolerance and laid-back habits par compared to native species can be catastrophic for local fauna.

New research shows that goldfish consume significantly more than comparable fish in UK waters, eat more than other invasive fish and are also much more willing to attack other competing species aggressively.

This means goldfish pose a triple threat, according to Dr James Dickey of Queen’s University Belfast, the study’s lead author.

“Not only are they readily available, but they combine insatiable appetites with bold behavior,” he said. “While northern European climates are often an obstacle to the survival of non-native species in the wild, goldfish are known to be tolerant of such conditions and could pose a real threat to native biodiversity. rivers and lakes, consuming the resources that other species depend on.”

The study was unable to assess whether more goldfish were being released back into the wild by pet owners who purchased new fish during the lockdown, but anecdotal reports suggested this could be the case.

“Although our research has not focused on whether this problem has worsened since the lockdown, there is reason to believe that it is, or at least will be, the case,” said Dickey said.

“There have been recent reports of the discovery of Amazonian catfish released in Glasgow which may be linked. There may also be a time lag, and it may not be until this summer, when normalcy resumes and, for example, people want to go on a trip [and leave their pets behind]that we are beginning to see the effects.

The study, published in the journal NeoBiota on Wednesday, looked at the two most commonly traded fish species in Northern Ireland: goldfish, which is an invasive species worldwide, and white mountain minnow, which is n has not yet established much of an invasive species. anchoring. Both species are part of the carp family and are native to East Asia.

The researchers established a new method to assess and compare the impacts of the two species by examining availability, feeding rates and behavior. By these standards, the goldfish far surpassed the white minnow and proved capable of wreaking havoc on native wildlife populations in UK ponds, rivers and streams.

Goldfish feed on tadpoles and other small fish when released into UK waterways, disrupting natural ecosystems.

In the United States, goldfish have been found to grow to over 30 cm (1 foot) in length in some waterways, due to their adaptability.

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Many pet owners feel they are acting humanely when releasing their goldfish into the wild, but Dickey warned it was destructive.

Another way to limit the damage, according to the study, would be for pet stores to stock more alternative species that do not pose such an invasive risk.

“Goldfish are high risk,” Dickey said. “Limit the availability of [species, such as goldfish] along with better education of pet owners, this is a solution to prevent harmful invaders from establishing themselves in the future.

Flushing unwanted fish down the toilet is also a no-no, according to Dickey. But he said some pet shops will take the fish back, but not usually with refunds, and there are websites such as Preloved.co.uk where they can be donated or exchanged.

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