Your gerbil's ideal enclosure has plenty of space, a good branch to climb on, a nest box and lots of bedding material. The gerbil's efficient kidneys make cage maintenance a breeze: Gerbils excrete very little urine, so their cages don't smell bad. You will only need to clean the cage once or twice a week.
The Gerbil Enclosure
A 10-gallon aquarium makes a great cage for a pair of gerbils. For larger groups, pick a 15- or 20-gallon tank, always favoring the largest enclosure you can afford and find room for. It's fine to use a second-hand aquarium or one that is cracked and cannot hold water for fish anymore. Just be sure that it has a tight-fitting screen lid that will allow your gerbils good ventilation.
You can also choose to house a pair of gerbils in a large wire cage (at least 12 by 24 by 12 inches), but many owners say that gerbils will rub their noses bald as they chew the bars of these enclosures. Also, gerbils tend to kick their bedding out the sides of wire cages, causing quite a mess for a several foot radius around their enclosure. For these reasons, wire cages are not ideal. Also discouraged are the plastic module-type homes with lots of pre-fabricated tunnels; your gerbil can chew his way out through any flimsy joint in the tunnels and escape.
Cover the bottom of the aquarium with a thick layer of bedding. Shavings (aspen shavings, not pine or cedar) work better than sawdust, which can irritate the gerbil's respiratory tract. You can also choose corncob bedding or safe paper bedding product. You will also need to get a water bottle and a heavy ceramic food dish.
Nesting boxes sold for hamsters in your local pet store are not usually very durable. Thin plastic suffers in a gerbil enclosure, and you will find that your pets whittle these boxes down to nothing quite quickly, gnawing first at the edges around the box opening and then destroying the walls and ceiling at will. Instead, give your gerbil a large-mouth jar or clay flowerpot to build its nest in. A cracked flowerpot works just as well as an intact one as long as you sand down all the sharp edges. Shredded paper, tissues, and soft hay all make appropriate nest box beddings.
Feng Shui for Gerbils
Don't overcrowd your gerbils' enclosure. You need to leave room for them to run around and burrow freely, so choose simple cage extras that serve multiple purposes in the cage. A good example is a long, curly branch that is at once a chew toy and climbing equipment. The branch also serves as a lookout point for your gerbils.
When you clean your gerbil cage, you should put the objects in the cage back in the same space they were before. Cleaning is stressful enough for your pets – don't make them adjust to a whole new housing setup when you return them to their enclosure. After you wash down the aquarium with warm water and a pet-safe detergent, clean the food and water bottles thoroughly. Your gerbil's climbing branch can be returned to the cage unwashed. It bears your gerbil's scent mark, and its familiar smell will be comforting to your pets when they return to the otherwise clean, scent-free enclosure.