Fish-man of Liérganes (El hombre pez)

According to testimonies collected and published by Enlightenment writer Benito Jerónimo Feijoo (c.1720), Francisco de la Vega Casar disappeared while swimming in the Bilbao estuary on Saint John's Eve in 1674. Five years later, fishermen off Cádiz captured and brought to shore a human‑shaped, fish‑marked creature entangled in nets (dated 1679 in Feijoo's account). The fishermen took the being to the Franciscan convent in Cádiz where he was allegedly exorcised and questioned; the single intelligible word he later spoke identified him with Liérganes. He was escorted back to his family in Liérganes, where he lived for about nine years before returning to the sea and disappearing once more. Feijoo treated witness testimony as evidence and concluded that a fish‑man had appeared in Cádiz and lived in Liérganes for a time.

Contemporaneous accounts as summarized by Feijoo describe the creature as having an otherwise human shape and looking like a young man with pale/white skin and thin red hair matching the missing man's description. Observers reported fish‑like signs: a strip of scales running from throat to stomach, another covering the spine, and what appeared to be gills around the neck. He habitually walked barefoot and, unless clothed by others, often went about nude.

The being survived at sea and was capable of remaining at large in maritime conditions for years; fishermen reported it became entangled in nets and was difficult to secure. Initially it did not answer questioning in several languages; after days it uttered the word "Liérganes" and later muttered isolated words such as "tobacco, bread or wine." It ate with avidity when it did eat but could also go a week without eating. Behaviorally it was described as easygoing and obliging in simple tasks but socially unresponsive and minimally verbal. Clerical authorities subjected it to an alleged exorcism, indicating contemporaries regarded it as possibly supernatural or pathological.