Short tailed opossums (Monodelphis domestica) are from South America, and are 4-6 inches long (body only; their tail is almost as long as the body) with thick grey-brown fur. The tail is prehensile, meaning it can wrap around and hold onto things, and hairless. They are marsupials, although they do not have a pouch like most marsupials. However, their young are born quite premature and helpless, latch on to a nipple on their mother's abdomen, and stay there until they are further developed, like other marsupials. In the wild they will eat insects, spiders, and rodents. For this reason they are actually welcome house guests in their native countries. They are easily handled if tame from a young age, but should be kept as solitary pets because of their tendency to fight with other opossums. They are nocturnal so will be most active at night, although if they do awake they will be social during the day.
Housing: short tailed opossums are adept as escaping, so whatever enclosure is provided should be thoroughly escape proof. An aquarium (15-20 gallon) with a tight fitting lid, or a narrow-mesh wire cage should work well. The ambient temperature should be kept at 70 - 80 F. Bedding should be provided - corn cob litter or shavings (not cedar!) will work well. A nest box is also required (commercial woven nest, or a margarine tub etc.), and tissue or shredded paper (not newspaper) will be appreciated as nesting material. Branches for perching and climbing are needed - make sure they are non toxic and not treated with pesticides (parrot climbing toys and ladders also work well). In addition, a hamster wheel can be used to provide opportunity for exercise. Short tailed opossums are fairly tidy creatures and will usually pick a corner are area to use as a potty, so a litter pan can be placed here to make cage cleaning easier.
Feeding: this is still a new area for short tails and owners and breeders tend to feed a wide variety of things. It is possible now to get commercially manufactured short tail food (e.g. Brisky's Short Tailed Opossum Food, available on-line). Otherwise, a commercial insectivore diet probably provides the best basic diet, although some feed cat food, ferret food and a variety of other pelleted diets with success. Look for diets that are high in protein and low in fat. A variety of treats should be offered, including mealworms, crickets, fresh fruit and vegetables (offer a variety), and hard boiled egg. Feeding is best done at night, with items such as egg or chicken that will spoil removed after a short time. Occasional treats can include small amounts of cooked chicken and low fat yogurt. Using a general vitamin/mineral supplement is probably a good idea as well. Water is very important to short tails and they can dehydrate very quickly, so it is vitally important to make sure their water bottle is always accessible and filled with fresh water.
Handling: as mentioned above, short tailed opossums are best kept as solitary animals. A tame, often-handled young opossum will make the best pet (PawPrint Online recommends age 3-4 months to acquire a pet - when younger they can be quite nervous and hard to handle). Males and females have equal pet potential. They do tend to be very friendly and inquisitive when tame and will be an enjoyable and entertaining pet.
As with any other pet, the proper expectations, education and commitment is required to give a short tailed opossum a home. For further reading, an excellent site is Know Your STO - Short-Tailed Opossums - by Molly Joy.