Housing a tortoise requires learning a few basics that can be a challenge for the new keeper. They need plenty of space and good control over environmental issues like temperature, humidity, and lighting.
Tortoises should be outside whenever possible, but not all of us enjoy the right climate most of the year. If you have to keep your tortoises indoors, it is important to try to do it right.
Introduction to Housing Basics
A. Tub or tank
Small tortoises can start with a 20-50 gallon container- aquarium, storage tub, etc. I prefer those with clear or translucent sides when possible just for aesthetics (although an opaque side version probably makes a better 'hospital tub' since not seeing what is happening outside would cause less stress.)
B. Lighting and overhead heat
Your overhead lighting and heating options will depend on your situation, but can include ceramic heat emitters (CHEs), for heat without light, especially helpful at night, and UVB-producing bulbs to simulate sunlight. You can use a thermostatic control for the heater and timers for the bulbs.
Be sure to use a reflector with a ceramic socket for any bulbs that emit heat, and obey any other instructions that come with the devices. (Oh, and try to not use the clamps that often come with reflectors- hang it from some chain or something instead since the clamps fail so often.)
Use a thermometer to monitor the heat.
C. Bottom heat
You may need 'bottom heat' if your room gets cool, or if you want more control over the humidity. If you need it, get a waterproof heating cable, or a heating mat that is safe for the situation- most heating pads are too hot for plastic tubs while others cannot get wet. Follow directions when you install any electrical component. I strongly suggest a thermostatic heat control when using any heating system.
Get some hardwood mulch for a substrate. Cypress is common, but any hardwood mulch that does not smell of cedar or pine would work fine. Add about 3-4" to the habitat, sculpting in a hill or two if you can. In many cases, you can generate plenty of humidity by adding an inch or so of water to the bottom of the substrate, especially if you use bottom heat.
E. Shelters and hides
Always provide at least one good, snug, cool, humid, and dark hide. Big leafy plants make great hides as well, which leads us to...
Add some live child-safe plants for humidity, shade, 'air conditioning', etc. The amount of plant coverage varies by species- forest-dwellers like lots of shade, while grassland tortoises generally prefer open spaces. You can also add live mosses, hanging plants, etc.
Besides plants, you can decorate with things like a stone 'river' or pathway, hills, leafy vines (real or fake), etc. Many people use 'wallpaper' scenery behind the back wall to make it look more jungle-like.
See also the article on "Planting an Interesting Habitat" by Terry O'Connell
G. Water and food dish
Add a water dish. I prefer glazed ceramic plant saucers, but any washable saucer or pan would work. Aim for something you can sink to the rim, is big enough for the tortoise to completely sit in, is deep enough to go 1/2 way up the shell or so, and is easy to get into and out of. If a saucer is too deep for small torts, add rocks to the bottom to make it shallower.
A food dish helps keep the substrate clean and keeps the tortoise from accidentally eating the substrate. A simple food dish is just a folded piece of newspaper that can be tossed after use, but any flat, washable material can be used- margarine tub lids, etc.. Avoid food dishes that has tall sides the tortoise has to reach over or into.
H. Top cover and insulation
If the room is cool or dry enough to affect your habitat- and most are- you would probably benefit from a cover on top and/or insulation on the bottom or sides.
You can cover your habitat with the original container lid, foil, plastic wrap, a sheet of plastic, etc. Remember that your heater can damage many of these, and that UV light does not go through most glass or plastics. You may have to either make openings for this, or rig the lid up as a tent that goes over the lighting or heaters.
The more you cover it, the better you hold in the heat and humidity, but also the more bacteria, mold, and mildew can grow, the more it will smell, and the more problems will develop. To make it even more interesting, if you put vent holes up high, most of your hot, humid air will 'chimney' up and out. Putting the vents down lower, with just a couple very small vents up high, helps prevent this.
It may also help to insulate the habitat. A sheet of rigid foam insulation under the tub to get it off a cold floor, or some insulation around the sides of a tub to reduce heat loss can make a huge difference in keeping the tortoises nice and warm.
I. Cage mates
Other tortoises, same species-
Most tortoises neither want nor need cage mates, although some species, such as red-footeds generally do better in groups. If you DO keep more than one tortoise in a habitat, there are a couple rules to follow:
Other tortoises, different species-
Mixing species is generally frowned upon for several reasons, including issues like proving the right habitat for all of them, concerns over diseases that other species are not resistant to, and possible breeding issues. In real life, however, zoos, breeders, and casual keepers do it all the time. Tortoises with overlapping ranges are considered safer, and with good cares and research you should be able to house many species together.
Edited 4-3-2013 (C) Mark Adkins