To the average person’s mind, this isn’t a problem because the fish can easily survive in the wild as long as they have water, but to experts, it becomes clear that dumping pet fish that aren’t native to a region can cause a slew of problems for the surrounding environment.
One of the most popular species of fish to get dumped are goldfish, and when they get dumped into the wild, they get huge, sometimes weighing up to 1.9kg and growing to be the size of the football. At this point, they can really start wreaking havoc.
Image Credit: Murdoch University
Researchers from Murdoch University took to mother nature to learn more about what was going on. They tracked the movements of goldfish and their findings have been published in the journal Ecology of Freshwater Fish.Goldfish have been known to behave a lot like carp, stirring up all of the natural sediments that make up the floor of a body of water as they swim close to it and contaminating the surrounding water in the process.
“They cruise along the bottom stirring up the substrate with their feeding strategy” said Dr Stephen Beatty from the Center of Fish and Fisheries. “This can re-suspend nutrients into the water column which exacerbates things like algal blooms. They can also disrupt aquatic plants and eat other fish's eggs.”
Moreover, they eat whatever they can find, including the eggs of other species of fish, and they don’t settle in just one area; they travel great distances and cause problems anywhere they swim to. In some cases, they’ve been known to spread certain diseases among other fish.
“Once established, self-sustaining populations of alien freshwater fishes often thrive and can spread into new regions, which is having a fundamental ecological impact and are major drivers of the decline of aquatic fauna,” Dr Beatty continued.
Their behavior is very hard on the rest of the native fish populations, and that’s why goldfish pose a threat to their local environments when local pet owners simply dump them into nearby natural water sources.
All of these bad effects on local ecosystems spell out a good reason for why people need to stop dumping their pets into the wild.
Source: Murdoch University via ABC News