I agree that you can use one. As mentioned, aquariums have thicker glass and are much heavier than a terrarium. They also tend to have relatively narrow dimensions. I would want one that is at least 18'' in depth/width. The main downside of using a large aquarium is that you will need to access everything from above. This may become a hassle compared to having a terrarium with front access. If you're OK with those downsides, go for it if you've found a good deal.