Former pet goldfish can grow to monstrous sizes and are causing problems in Minnesota. Goldfish have been released and found in all corners of our state, when someone takes their pet and releases it in the lake, this is considered illegal fish stocking
Authorities in Burnsville, Minn., have urged residents and owners of pet goldfish not to dispose of the family pet in lakes and ponds. The city tweeted a warning that doing so has resulted in the takeover of one local lake by overgrown goldfish.
“They grow bigger than you think and contribute to poor water quality by mucking up the bottom sediments and uprooting plants,” authorities wrote on Twitter. “Groups of these large goldfish were recently found in Keller Lake.” They suggested that if you have a goldfish that you can no longer take care of to either have it adopted, or contact your local veterinarian for humane disposal.