The chapter discusses some of the trends, looking at the multiple reasons for the so-called aquarium craze of the 1850s and early 1860s. It suggests that the way in which Victorians enjoyed and conceptualized the marine tank was deeply imbricated with various aspects of coeval culture, reflecting the beliefs, assumptions, and preoccupations of its owners. Victorians enthusiastically embraced the aquarium also because it reflected them in many ways, but at times the tank could also turn into a dark mirror. Decorative features typical of mid-Victorian gardening were adapted for aquaria; rockeries, grottoes, and arches in particular were deemed very desirable, as they offered a touch of the picturesque. The chapter investigates what early aquarists saw in the tank, in order to better understand the way they experienced it, which was rich, impressively multi-layered, and culturally specific. It considers some of the difficulties inherent in a hobby that could involve a significant amount of commitment, dedication, and expense.