For years, in Girona, on the Onyar river, there have been some small animals that arouse great curiosity among residents and visitors. They are coypus, large rodents, over two spans long, that swim among the carp and forage along the water's edge. They are not only present in the Girona river, but also in the Sils ponds, the Empordà wetlands, and along the entire bank of the Baix Ter. They arrived in the Girona regions from France, as a result of human activity linked to the fur industry, and have spread throughout the province to areas in the south like La Selva. Despite their cute and harmless appearance, with very large orange front teeth, these animals pose a problem for the natural ecosystem, as they are an invasive species, one of the most harmful in all of Europe, which damages flora and alters the habitats of native mammals. They are herbivores and feed on large quantities of vegetation, so they also cause damage to crops, especially wheat and rice in wetlands.  

The coypu on display from the Onyar River near Girona create a great deal of excitement among passersby crossing the city's bridges. They are in greater demand than the classic carp, which has also been cornered by the Ebro thornback, another much more abundant foreign species that can reach comparable sizes. The coypu have found in the lower reaches of the river that runs through Girona, with its calm waters, rich vegetation, and naturalized banks, a perfect ecosystem for reproducing and forming families. They can be seen on the riverbanks or swimming in the water, and they do not flee at the presence of humans.