Choosing a proper enclosure is important to the well-being of your pet. Remember that aquariums are designed for fish not mammals. They are a bad choice for guinea pig housing because they are poorly ventilated, which allows excess moisture to build up in the corners of the tank.
Also, the smooth glass walls make it awkward to attach necessities such as food bowls, water bottles, and hay racks. Variable wire cages with plastic floor, available at most pet stores, are recommended
An ideal cage is well-ventilated and large enough for your guinea pig, his food bowl, water bottle, toys, a hide box, and room for roaming