The story of the Spanish Wels catfish traces back to a single, reckless act. In 1974, a German biologist and sport fisherman named Roland Lorkowsky drove across the Pyrenees carrying thousands of juvenile *Silurus glanis* fingerlings native to the Danube basin. He emptied them directly into the Ebro River below the reservoir dam of Mequinenza.
Lorkowsky sought to establish a premier sport-fishing quarry in Southern Europe. He succeeded beyond his wildest expectations, triggering an environmental disaster in the process. The warm, nutrient-rich waters of the Ebro offered an ideal habitat free of natural predators. Indigenous species, including the Ebro barbel (*Luciobarbus graellsii*) and native nase, had evolved zero defensive behaviors against an ambush predator that grows past eight feet in length.
Within two decades, the Mequinenza Reservoir became known across Europe as the "Sea of Aragon." Thousands of German, British, and French anglers arrived each season, turning small towns like Caspe and Riba-roja d'Ebre into bustling angling hubs. Guiding outfits charge anywhere from €350 to €700 per day for guided drift-boat excursions, fueling a multi-million-euro regional hospitality trade. Beneath the surface, native fish biomass dropped precipitously as the siluro consumed everything from crabs and waterfowl to small mammals.
