A wire cage, a few hectares of land in the French region of Haute-Savoie, and fifteen small mammals with silky fur imported from North America—this scene may seem harmless or even picturesque. However, it set in motion a chain of events that disrupted the balance of French rivers for nearly a century. The American mink, introduced in 1926 to meet the rising demand for fur, became one of the most dramatic examples of how an invasive species can devastate native wildlife. Today, the European mink, a predator that once thrived in French rivers for thousands of years, survives in only a few hundred individuals across the country. The story begins in 1926, when five male and ten female American minks were brought to Haute-Savoie to start fur farming in France. At the time, mink fur was highly prized for its softness and durability, becoming a symbol of elegance for women in the early 20th century. French breeders saw an opportunity and quickly expanded the industry. By 1959, over 600 mink farms were operating in France, with little regard for the ecological consequences of housing such a large number of carnivorous, opportunistic animals near rivers and wetlands. Despite attempts to contain them with fences, American minks frequently escaped or were released when farms closed down, leading to their spread across the country. Once established in the wild, the American mink outcompeted the European mink for resources and territory. The two species share similar habitats and prey, but the American mink is more adaptable, aggressive, and less reliant on riverbanks. This behavioral difference gave it the upper hand in the struggle for survival. Ecologists refer to this process as competitive exclusion, where one species gradually pushes another out of its niche. The European mink, unable to compete, has been forced into a shrinking habitat. As of 2011, it was classified as critically endangered, with fewer than 250 individuals remaining in France, mainly in the Nouvelle-Aquitaine region. In response to this decline, recent conservation efforts have focused on reintroducing the European mink to the wild. However, the road to recovery is long and challenging. As long as American minks continue to thrive in French rivers, the European mink will face intense competition for food and space. The impact of the original 1926 introduction of American minks serves as a stark reminder of how human economic decisions can have lasting, unintended consequences on ecosystems. Today, the fate of the European mink hangs in the balance, as scientists and conservationists work to restore a species that once roamed freely across the country’s rivers.