Chinchillas need to be housed in a wire cage with openings no larger than 1 inch x 2 inches. If you are getting a young chinchilla or are planning to have babies in the future the openings should be 1/2" x1". They love to chew and will escape from a cage made with a plastic bottom. Aquariums do not have enough ventilation and a chinchilla will overheat in one. If you use a wire floor cage be sure the wire opening are no larger than ½”x ½”. You should add a wooden box or shelf to the cage so that the chinchilla won't have to stand on wire all the time. Cages with solid bottoms are a good choice. Chinchillas tend to make a bigger mess using this type of cage because they can push shavings out at night while they are playing, but I like this type better. There is no chance of foot injury from slipping through the wire floor and the shavings are warmer and eliminate drafts. This type cage is especially good for breeding since babies can die quickly from a chill when they are first born. Make sure that the cage you choose will give your chinchilla plenty of room to move around. Chinchillas need to be able to climb, run around, and play. They have a lot of energy, and need exercise. If your cage is too small and your chinchilla can't run around outside the cage regularly he will become very unhappy. We recommend 24"x24" as a good starting size with enough height to include a shelf or two