Goldfish are remarkably common pets in the US.
They’re relatively low maintenance and can be a lot of fun to watch making them popular with people who want a pet but are unable or unwilling to invest the kind of time and money needed for pets like cats or dogs.
Even though keeping them is less labor-intensive than maintaining most other pets, sometimes they just don’t seem to flourish.
When that happens, sometimes fish owners release them in nearby bodies of water or flush them down the toilet as a method for disposing of the remains. The problem is, though, the little creatures aren’t always dead.
Goldfish are members of the carp family, and in captivity they generally stay very small, rarely reaching up to six inches, according to the New York Department of Conservation.
When one of those little swimmers is released illegally or survives a trip down the commode, however, it can be a whole different story.
According to a recent story an employee of the non-profit organization Buffalo Niagara Waterkeeper recently had his hands on a goldfish found in the Niagara River which reached 14 inches long.
This sizable carp isn’t the first or the largest goldfish ever found in open waters. One was caught in Lake Tahoe in 2013 that was nearly two feet long and weighed four pounds.
At this point, more than half of the fish in the Lake Tahoe basin are invasive species that came from other places.
In 2017, at a dam project near Parma, Ohio, workers found a number of very large goldfish in a nearby lake, several of which were between two and three pounds each.
Such finds can cause – ahem – a really big problem in the lakes and rivers where the fish now live.
Outside of the limits of a fishbowl or small aquarium, it’s not unusual for goldfish to become radically larger than they do in captivity, and to prolifically reproduce.
Goldfish were first domesticated about two thousand years ago in China, as a food source. Over time, they made the transition from supper to pets, and their popularity began to spread around the world, reaching North America by the 18th century.
In New York, the first sighting of a goldfish in the wild occurred in 1842, and by the end of the 19th century, 19 other states were also reporting them.
Once they’re released by well-meaning, if irresponsible pet owners, they become an invasive species that can survive year-round in some environments and can reproduce very quickly.
In one lake in Colorado, just a few of the fish turned into a population of thousands in the span of only three years.
Besides being able to reproduce quickly, they also have substantial appetites, eating everything from plants to insects to other fish.
Once the population begins to grow, the goldfish are in competition with the other, native fish for food and are so enthusiastic about eating that they can actually stir up sediment and mud to the point that they can create algae blooms, even further compromising the ecosystem, according to a 2018 report from Business Insider.
As if that weren’t problem enough, goldfish can bring new parasites and diseases into areas that didn’t have them before, exposing native fish who have no natural defenses to them.
They are also willing to travel and can cross multiple bodies of water in their lifetimes. A few of the fish were dumped into an Australian River in the early years of the 2000s, and they eventually made their way to the Vosse River, where they can still be found.
Goldfish start out as small pets that most fish owners only pay a few dollars for. When they’re released into the wild, their growth, appetites, diseases, and ability to migrate combine to cause very expensive cleanups and ecosystem repair in the bodies of water they inhabit.
Yes, water is a fish’s natural element, but not all watery environments are the same.
Wanting to ‘free’ a goldfish into its ‘natural environment’ may be an intended act of kindness to that one fish, but it can cause a cascade of problems for all the rest of them.