Goldfish Dumped in Lakes Grow to ‘Monstrous’ Sizes, Threatening Local Species


Jul 14, 2021


Image credit: Murdoch University

Authorities in the U.S. last week requested people to stop dumping goldfish from aquariums in lakes — noting how they grow into “monstrous” sizes, and threaten the native species of the water bodies.

“They grow bigger than you think and contribute to poor water quality by mucking up the bottom sediments and uprooting plants,” authorities from the City of Burnsville in the U.S. tweeted.

When outside a small aquarium, goldfish can grow significantly in size — suggesting their capacity to grow is dependent on the environment they’re put in. Unfortunately, however, when they are released into a lake’s ecosystem, they begin competing for resources with native species. Moreover, “when an organism moves into a territory where it lacks natural predators, it can interrupt the entire ecosystem by scarfing down local resources and killing important species,” Rachel Feltman, a science journalist, wrote in the Washington Post in 2016.

However, this isn’t the first time aquarium owners have disrupted the ecosystem by releasing goldfish into natural water bodies. Australia and Canada have reported cases, too, with a news article from the Canadian Broadcasting Corporation stating: “Goldfish the size of dinner plates are multiplying like bunnies.”

“Perhaps they were kids’ pets where the family have been moving house, and their parents, not wanting to take the aquarium, have dumped them in the local wetlands,” Stephen Beatty from the School of Veterinary and Life Sciences at Murdoch University in Australia told ABC News in 2016.

“Unfortunately, a lot of people don’t understand that wetlands connect up to river systems, and introduced fish, once they get in there, can do a lot of damage to native freshwater fish and the aquatic habitat,” Beatty added.

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Besides the goldfish, other “aquarium species” are also dumped into waterbodies — disrupting ecosystems. The phenomenon of fish from aquariums being dumped into lakes has been observed in India, too.

In Hyderabad’s Neknampur Lake, Alligator gar, a North American freshwater fish was discovered earlier this year. “These fish are not found in Indian rivers and lakes. They are grown for aquariums, and when they become too big to handle, people leave them in lakes,” said Madhulika Choudhary, a conservationist and founder of Dhruvansh, the NGO that adopted the Neknampur Lake. “If you can’t care for them, why do you keep them,” she added.

“They are predatory in nature, and can wipe out the entire lake of its biodiversity… They are aggressive in nature and kill other pond turtles such as pond terrapins and flap shell turtles. Exotic species are dangerous for native ones,” Choudhary added.

In April this year, a freshwater fish from South America was eating up the eggs of native species in the Neknampur Lake, disrupting the ecosystem.

This March, the sailfin armored catfish, also known as suckerfish was found by fishermen in Goa. “The suckers are hardy and can survive without water for over a day. They compete with natural fish populations and create their own territories in water bodies,” G.B. Sreekanth, a fisheries scientist at the Indian Council of Agricultural Research, told the press. The species is already known to have invaded Kerala’s water bodies.

“Awareness needs to be created among the people who keep aquariums as a hobby not to release the suckerfish in wells and ponds,” Shamila Monteiro, the Director of Fisheries in Goa, had recommended.


Written By Devrupa Rakshit

Devrupa Rakshit is an Associate Editor at The Swaddle. She is a lawyer by education, a poet by accident, a painter by shaukh, and autistic by birth. You can find her on Instagram @devruparakshit.


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