Zebrafish (Danio rerio) is a tropical freshwater fish of the cyprinid family, considered a welle stablished animal model in scientific research for ecotoxicological studies, cardiovascular diseases, and cancer research. During the Mednight day, a stand will be set up where the various stages of development of zebrafish such as embryos and larvae will be shown through the interactive use of a stereomicroscope, explaining the applications in scientific research. Zebrafish at the adult stage will also be shown through demonstration videos, showing to the public how to easily recognize male and female fish and how they reproduce.