Setting up

Match the enclosure to how the animal lives

Each species guide gives a minimum size. What kind of enclosure to buy depends on one question: does the animal need warmth and humidity held in, or air moving through?

Size and shape

• A snake's enclosure should be at least as long as the snake and at least half that in depth, so it can stretch out fully. You're better off buying the adult size once than upsizing three times.
• Tree-dwellers, such as crested geckos and chameleons, need height more than floor area.
• Space only helps if it is furnished. A large, bare enclosure is more stressful than a smaller, cluttered one. Fill it with cover (see Hides, cover and water) rather than choosing a smaller box.

Ventilation

A solid enclosure needs vents at both ends, low at the cool end and higher at the warm end, so air moves across it. Warm, saturated, still air is how respiratory infections start. A mesh enclosure has the opposite problem, and the species guide says how to hold enough humidity in it.

Security

Glass runners must run true and doors must take a lock. Snakes in particular push at gaps persistently, and an escaped reptile finds the coldest, dustiest place in your house and stays there.

The rules that do not change between species

Temperatures and UVB strength are different for every animal, and each species guide gives the numbers. The rules for how you deliver them are the same for all of them.

A warm end and a cool end

Reptiles have no internal thermostat. They regulate their temperature by moving towards heat to digest and away from it to rest. So set up a range, hot at one end and cool at the other, and let the animal choose. An enclosure heated evenly throughout gives it no way to warm up or cool down, even when the temperature is correct on paper.

Every heat source goes through a thermostat

An unregulated heat mat or bulb is the most common cause of burns in captive reptiles, and a thermostat that is present but wrongly matched to its heat source is nearly as bad.

• Guard anything the animal can reach. Ceramics, projectors and bulbs run hot enough to cause full-thickness burns, and reptiles do not reliably move away from a heat source that is burning them.
• Put the thermostat probe where the heat lands, on the basking surface under the heat source. A probe at the cool end drives the hot end far past its target.
• Measure air temperature with a digital thermometer that has a wired probe at each end, and surfaces with an infrared temperature gun. The stick-on dials sold in starter kits are not accurate enough to rely on.
• Check weekly with the gun, and again after anything changes: the heating goes on, the season turns, the enclosure moves, the power comes back after a cut.

Light and UVB

Whatever the species, a regular day and night is the minimum: lights on a timer, and an enclosure that is never in a permanently dark room. On top of that, reptiles are grouped into four Ferguson zones by how much sun they get in the wild, from Zone 1 shade dwellers such as royal pythons to Zone 4 open-sun baskers such as bearded dragons. Each species guide names the zone, the tube and the UV Index to aim for. For every zone:

• Replace tubes every 12 months. UV output falls away long before visible light does, so a tube that still glows may be giving almost no UVB.
• Mesh between the tube and the animal blocks a large share of the UV. Mount the tube inside where you can, and allow for the mesh where you can't.
• Fit UVB over the warm end, so the animal gets heat and light in the same place, with shade elsewhere to retreat to.

Fire and electrical safety

A reptile room runs several heat sources around the clock. Use a proper multi-way extension rather than daisy-chained adaptors, route cables where they cannot be chewed or wetted by misting, keep heat sources clear of décor and paper, and fit a smoke alarm in the room.

Measure it, then control it with the setup

Targets vary more than any other number between species. A bearded dragon wants dry desert air; a crested gecko wants humid air at night, like a forest floor. The species guide gives the figure. How you measure and adjust it is the same everywhere.

Measure

Use a digital hygrometer, placed at the level the animal lives at. Analogue dials are as unreliable as analogue thermometers.

What wrong looks like

• Too dry: shed coming off in patches, retained eye caps on snakes, rings of old skin left on toes and tail tips of lizards, which tighten and can cost the animal the tip.
• Too wet, especially wet, cool and still: scale rot, respiratory infection, mould on the substrate and décor.

Spraying, and the humid hide

Misting raises humidity for an hour or two, then it falls again. That makes it useful for species that drink droplets, such as chameleons and crested geckos, but no use for holding humidity steady; substrate and water do that. A humid hide (any hide packed with damp sphagnum moss) gives snakes and leopard geckos a permanent damp microclimate they can use when they shed, without making the whole enclosure wet.

What goes on the floor

Substrate holds humidity (or doesn't), gives the animal something to dig or push into, and decides how easy the enclosure is to keep clean. Each species guide names its best choice; this is the full comparison.

• Depth: enough to dig or push into, typically 5-10 cm for burrowing and ground-dwelling species. The species guide gives the figure.
• Spot-clean droppings and the substrate around them as you find them. A full change every 4-8 weeks on a standard setup; an established bioactive enclosure goes far longer.

Give the animal somewhere to feel safe

An animal that will not eat, sits in its water bowl, paces the glass or hides and never emerges is very often an animal that does not feel safe. Before changing anything else, look at its cover.

Ground-dwellers: snakes, leopard geckos, bearded dragons

• Put a hide at each end of the gradient, and make the two identical. If one is nicer or roomier, the animal is forced to choose between the temperature it needs and the shelter it prefers.
• Choose snug hides. A correctly sized hide has the animal touching the sides and roof when curled up. Upsize as it grows.
• Clutter the open ground with cork bark, branches, rocks secured so they cannot fall, and artificial or live plants. An animal crossing bare floor has nowhere to hide.

Tree-dwellers: crested geckos, chameleons

For these species, cover means foliage: dense planting, live or artificial, and branches and vines at several heights so the animal can climb between warm and cool, bright and shaded, without crossing open space.

Water

Change bowl water two to three times a week, and at once if fouled.