The eel, a mysterious fish with its poisonous blood and disquieting, snake-like appearance, has been much appreciated since ancient times as a delicacy and has been fished since time immemorial along the Tresa river.
The river, which flows into Lake Como, was in fact an ideal environment for catching eels, before dykes and locks prevented their migration towards the Sargasso Sea, where adult specimens reproduce.
The existence of eel ponds along the course of the Tresa river is documented with certainty from 1476 onwards, when a deed drawn up by the notary Giorgio Avanzini di Curio mentions both the Peschiera di Sotto, which was owned by Ser Filippinus del Albis di Sessa, and the Peschiera di Sopra, situated towards the mouth of the river, meaning that any revenues from it went to the archiepiscopal see of Milan.
In 1583, Archbishop Charles Borromeo ceded ownership of it to the Perseghini family of Ponte Tresa. Later, other important local families came into joint ownership of it as compadroni: these included the Bella, Crivelli, Giani, Rossi, de Stoppani and Quadri families.
Eels were a delicacy, in great demand among the well-to-do classes, and the eel trade gave rise to a small economy in itself. The traditional grottos of the Tresa valley served them as a speciality, either stewed or on a spit, while the owners of the peschiere transported them live in barrels full of water to Milan, to the German-speaking part of Switzerland, and even as far as Paris.
Bulky constructions doomed to hinder the flow of the waterways, straddling ill-defined boundaries, subject to uncertain legislation, these peschiere or eel ponds were the subject of countless disputes, thanks to which we have ample documentation of their operation from the 16th century until they were permanently abandoned as a result of damage caused by the floods of 1951.