As the Middle Ages drew to a close, however, a rising share of Europeans were eating fish from systems other than their natural local waters. By 1500 around Paris, for instance, elite menus featured carp and headless codfish, while lesser folk made do with herring and haddock. Beside the Mediterranean, Valencia was receiving millions of Atlantic sardines and hake, while Romans could get herring from the North Sea, Norwegian cod, and tuna from Sicily. Both cultured carp and fishes from Europe’s economic frontiers changed Europeans’ relations with aquatic nature.

Carp aquaculture colonized nature, creating artificial habitats to rear an organism alien to western Europe. Late fifteenth- and early sixteenth-century financial records and instructional manuals from east-central Europe detail an original and distinctive European mode for farming fish. Those practices provide a benchmark to identify and trace their creation in twelfth- to thirteenth-century France – where the carp was a late invader – and subsequent spread eastwards of the innovation. Human-controlled aquaculture created thousands of local ecological revolutions across interior Europe, providing inland elites with a steady source of live fresh fish, serving as a vehicle of elite power over subjected nature and people, and replacing indigenous ecosystems with private anthropogenic habitats tailored for domesticated, soon also feral, invaders. For contemporary writers fish had become objects of human agency.