HOME FOR PET FISH can be summarized as an AQUARIUM or TANK, which are both containers used to house pet fish. An AQUARIUM is an enclosed glass or plastic container that is filled with water and often decorated with plants, rocks, and other decorations. A TANK is a larger, more open container that is also filled with water and can be used to house pet fish. Both aquariums and tanks provide a safe and comfortable environment for pet fish to live in.