Short-tailed Opossum

House one adult in a secure glass tank or fine-mesh cage of at least 60 x 45 x 45 cm (roughly a 75 litre / 20 gallon long tank); bigger is better and both floor area and some vertical climbing space are valued. A tight-fitting, clip-locked lid is essential because they squeeze through gaps under 1 cm and are strong climbers. Provide 5 to 8 cm of paper-based or aspen bedding for burrowing (avoid aromatic cedar and pine shavings). Key furniture: an enclosed nest box or hide stuffed with tissue/fleece for daytime sleeping, sturdy branches and cork for climbing, and a large solid-surface (rungless) exercise wheel of at least 28 cm diameter to burn energy and prevent obesity. Use a sipper water bottle plus a shallow dish.

An insectivore-leaning omnivore. Base the diet on a high-quality insectivore or exotic-omnivore pellet (or a low-fat cat/ferret kibble as used in research colonies), rotated with live gut-loaded insects such as crickets, dubia roaches, mealworms and the occasional waxworm as a treat. Add small amounts of lean cooked meat or egg, a pinkie mouse once every week or two for adults, and a little chopped fruit or vegetable for variety. Dust insects lightly with a calcium (plus vitamin D3) supplement to prevent metabolic bone disease, but do not over-supplement. Keep portions small and fatty foods rare, as obesity is the number-one captive problem. AVOID entirely: chocolate, caffeine, avocado, onion, garlic, alcohol, and salty or sugary human foods; go easy on fatty insects like waxworms.

Keep the ambient range at about 21 to 27 C (70 to 81 F), ideally around 24 C (75 F), with a gentle thermostat-controlled warm spot of roughly 27 to 29 C at one end created by an under-tank heat mat; always leave a cooler retreat so the animal can move off the heat. This is a warmth-dependent tropical species that is PRONE TO CHILLING and has a lower body temperature than similar-sized rodents, so supplemental heat is often needed whenever the room falls below about 21 to 22 C, especially at night. At the same time, avoid sustained temperatures above roughly 30 C and never combine high heat with high humidity and poor ventilation, which risks heat stress. There is no basking requirement as this is a nocturnal mammal, not a reptile; UVB lighting is not required and a normal day/night light cycle is enough, with bright light avoided during their active night hours. Humidity should be moderate, ideally around 40 to 60 percent (they tolerate roughly 30 to 70 percent).

Strictly solitary and territorial. Adults must be housed one per enclosure; cohousing typically leads to fighting, stress, and injury, and even pairs introduced for breeding are separated again promptly after mating. Sexing is by the male's slightly larger size and scrotal position of the testes versus the female's ventral abdominal glandular area (this species lacks a true pouch). Sexual maturity comes early, around 4 to 6 months, so littermates must be separated before then to prevent fighting and unplanned breeding.

Being intelligent and highly active at night, they need plenty to do. Rotate deep burrowing substrate, climbing branches, cork tubes, cardboard tunnels and multiple hides. A large solid exercise wheel is both enrichment and obesity prevention. Scatter-feed insects and use foraging or puzzle feeders so the animal has to hunt and work for food rather than eating from a bowl. Vary the layout periodically to keep the environment novel, and let it explore in a secure escape-proof playpen under supervision.