Every day hundreds of little goldfish (Carassius auratus) find a new home. Some will stay in luxurious aquariums with other companions with whom they will spend the days swimming and eating; Others will have to live together in a small, more austere fish tank, resigning themselves to solitude, but a final group will have the opportunity to live in freedom, thanks to the decision of their human owners. One might think that this altruistic gesture is the most appropriate, since it guarantees the well-being of the golden carps. However, in practice, the release of these animals in any marine environment can cause irreparable problems in their environment.
And it is that, as small and docile as they may seem inside a fish tank, goldfish are true destroyers of biodiversity. This is what a group of scientists from the University of the Queen of Belfast (Queen’s University Belfast) and the Leibniz Institute of Ecology, in Northern Ireland and Germany, warn that in a recent article published in NeoBiota have estimated that, due to its nature and easy availability on the market, this fish has all the ballots to become an invasive species.
“Our research suggests that goldfish represent a triple threat,” says the paper’s lead author, ecologist James Dickey. These animals can not only be easily found in any establishment, but they also have behavioral characteristics that play in their favor when it comes to dominating any ecosystem, such as their audacity and insatiable appetite.
It also adapts very well to cold climates, not just temperate ones. “Although the climates of northern Europe are often a barrier that prevents non-native species from living in the wild, goldfish tolerate such conditions,” says Dickey, who insists that “these characteristics make them in a “real threat to native biodiversity in rivers and lakes”, because it can consume the resources on which other species depend.
To reach this conclusion, the researchers developed a method to assess the ecological impacts and risks of the pet trade, given that this activity generates a third of the aquatic invasive species that spread in rivers and lakes. To understand the ecological risks of the aquatic pet trade, the researchers focused their efforts on two of Northern Ireland’s most-traded species: goldfish and white cloud mountain minnow.
The scientists studied the availability of these fish in the market, how much they ate and their behavior. The study concluded that golden carps are voracious; in fact, they consume much more food than the so-called white cloud mountain minnow (Tanichthys albonubes) -common in fresh and cold waters- and other species native to the region.
In Spain, as reported by the Ministry of Ecological Transition, the populations of golden crucian carp that live in free waters are currently very sparse, so today they are not considered a conservation problem. However, due to its exotic nature, it seems advisable to at least limit its expansion, favored by the use made of this fish as live bait.
“Golden carps carry a high risk”, says Dickey, who hopes that the methods they have developed can be replicated to study other fish that are sold as pets. Likewise, he recalls that “species that can be easily purchased are more likely to be released” into the wild. For this reason, he emphasizes the need to limit their trade, while at the same time providing their owners with a better education: “It is a solution to avoid damage in the future,” he insists.
Reference study: https://neobiota.pensoft.net/article/80542/
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