Guava leaves , from the Psidium guajava , are used in terrariums to enrich bioactive soils, provide hiding places, and promote the growth of beneficial microorganisms. They help maintain humidity and provide food for scavengers such as woodlice and springtails. In aquariums, they release tannins and have antifungal and antibacterial properties, contributing to the health of the ecosystem. Their durability and natural appearance make them an excellent addition to bioactive habitats.