This chapter takes a closer look at the practice of wet preservation, the conservation of formerly living material in alcoholic fluids. While wet preservation was widely used for various species in the 18th century, this study focuses on a specific challenge within the field of early modern taxidermy: the preservation of fish. Due to their unique physical properties—fragile skin, soft tissue, and rapid decay—water creatures represented a special case in both collections and taxidermy. Their conservation required adapted techniques and raised fundamental questions about how animal bodies could be conserved, visualised, and made permanently available for study. Introducing a wet specimen from the collection of Marcus Élieser Bloch (1723–1799), one of the most prominent ichthyologists of the 18th century, this chapter sheds light on the interplay of human actors and dead animal bodies. The object’s close reading is complemented by a selection of contemporary visual sources and manuals such as Wolfgang Jäger’s Anweisung, wie die verschiedenen Seltenheiten der Naturgeschichte zu sammeln, zuzubereiten, zu erhalten und zu verschicken sind (1761), Friedrich Benjamin Osiander’s Abhandlung über das vortheilhafteste Aufbewahren thierischer Körper in Weingeist (1793), and William Swainson’s Taxidermy (1840), thus tracing the emergence and refinement of (wet) preservation techniques from the mid-18th to the mid-19th century. Together, the specimen and textual evidence illuminate the evolving strategies and tensions in preserving aquatic life— and highlight the fish jar as a field of experimentation between knowledge production and aesthetic practices.