The answer to the question of whether or not it is bad to have a bare bottom aquarium really depends on what type of fish you are keeping and their needs. For example, some species such as goldfish tend to thrive in bare bottom tanks since they don’t need any substrate for burrowing and rooting around, but other species such as cichlids may require a more complex environment with sand or gravel substrate. Additionally, having a tank without any substrate can make it much easier to keep clean, since there will be no organic material accumulating at the bottom that could potentially cause issues with water quality. On the other hand, bare bottoms lack the natural appearance that many hobbyists prefer and they also offer fewer hiding places for shy fish. In short, if you are keeping fish that do not require an elaborate setup then having a bare bottom aquarium can work just fine; however if your tank inhabitants need extra enrichment then adding in an appropriate substrate might be necessary.