Football-sized goldfish found in Burnsville [MN] lake, prompting plea not to dump pets

Star Tribune ^ | JULY 12, 2021 | Erin Adler

[BenLurkin]

Burnsville officials found 10 fish, some a foot long, in Keller Lake earlier this month while surveying the fish population as part of a water quality project. On Monday, a second trip yielded 18 more fish, some 18 inches long and estimated to weigh about 4 pounds.

The proliferation of the bright orange fish, which don't naturally live in Minnesota waters, is a problem that's plagued communities around the metro as pet owners seeking a humane next chapter for their pets — which hail from east Asia and are a smaller cousin of the common carp — end up adding an invasive creature to their local waterways. It is illegal in Minnesota to release goldfish into waterways.

Goldfish, which reproduce rapidly and have few natural predators, im­pair wa­ter qual­i­ty by feed­ing along lake floors, dis­rupt­ing plants and stir­ring up sed­i­ment, which in turn re­leas­es phosphorus into the wa­ter, en­cour­ag­ing al­gae growth. The fish also com­pete with na­tive spe­cies for food.

[piasa]

Usually when they breed outdoors the ones that survive to breed and grow are the ones with the poorest color, so in short order, in certain bodies of water, you have tons of silvery goldfish doing all the breeding, not bright gold ones. It is those silvery survivors that proliferate and become a nuisance because many of them get big enough to avoid the usual predators.