Top Fin aquariums are made of either glass or acrylic, depending on the model. Glass is the traditional material used for aquariums and provides superior clarity while being stronger than acrylic. However, it is heavier and more expensive than its counterpart. Acrylic is lighter in weight and less expensive but can scratch easily over time. It also has higher insulation properties to help maintain a stable temperature in the tank. Ultimately, you should select an aquarium based on your needs; if you want something sturdy that will last longer then go with glass, but if pricepoint and portability are important factors then consider an acrylic tank instead.