Both Argentine and Colombian tegus require 12-14 hours of daily exposure UVB for their health. In captivity, this should be supplemented by opportunities to bask in “real” sunlight as often as weather permits.
The best way to provide UVB for your tegu is by using a fluorescent UVB bulb designed for high output. While the Zoo Med Reptisun 10.0 T5 HO might work for hatchling enclosures, it’s not strong enough for use in a larger enclosure. For yearlings to adults, I would recommend the Arcadia HO T5 14% lamp.
PRO TIP: HO (high output) bulbs require fixtures designed for high output bulbs. Without the special fixture, HO bulbs don’t get enough electricity and can’t work correctly.
What is UVB?
UVB is a form of radiation produced by the sun. All animals produce vitamin D3 via exposure to these rays, including humans (although when we bask in them for too long, we get a sunburn because we don’t have scales to protect us). Vitamin D3 is important for metabolizing calcium. When tegus don’t get UVB, they can become D3 deficient, which leads to Metabolic Bone Disease.
Tegu Temperatures & Heating
Tegus are cold-blooded, which means that they are dependent on their environment for the warmth that is required for them to be able to move, digest, and carry out other metabolic functions. It also means that they can’t control their internal temperature. If a tegu gets too hot, can’t sweat or pant to cool itself down; instead, it must move out of the heat to cool down. Providing both warm and cool areas in the enclosure is called a temperature gradient.
The ideal temperature gradient for tegus is as follows:
- Basking — 110-115°F (43-46°C) for juveniles, 125-135°F (52-57°C) for adults
- Warm side — 90-95°F (32-35°C)
- Cool side — 75-85°F (24-29°C)
Temperatures can safely drop down to 70°F (21°C) at night.
To make sure that you have the right temperature in each area, you will need an infrared temperature gun like the Etekcity Lasergrip 774. These handy tools offer pinpoint temperature readings for anywhere in the enclosure — a true must-have for any reptile owner.
How to heat a tegu enclosure
For hatchling tegus, a high wattage halogen floodlight bulb should provide enough heat to get the basking spot up to temp.
Once your tegu reaches yearling size, you may notice that a floodlight bulb doesn’t provide a basking spot large enough for the tegu’s entire body. Because yearling and adult tegus are so large, it’s more efficient to use a series of lower wattage halogen flood lights clustered together, creating a proportionally larger basking zone.
Place a hide on the cool end of the enclosure to give your tegu a secure place to retreat from the heat. Providing a place where they can dig their own burrow is also an option. (See Substrate Options for Pet Tegus)
In theory, the bulb on the basking side of the enclosure should provide enough warmth to create the necessary temperature gradient in the rest of the enclosure — especially if you aren’t using an all-glass terrarium. If for some reason this doesn’t work, you may install a CHE (ceramic heat emitter) to get the low end up to temp, especially during winter. You can control how hot the CHE gets with a lamp dimmer from your local hardware store.
Tegu Humidity Levels
If you look at tegus’ native habitat, you’ll notice that they are evolved to thrive in a high humidity environment. To replicate this environment in your tegu’s enclosure, strive to hit 70-80% humidity.
You can hit these humidity levels with two tricks:
- Mix water into the substrate until it is uniformly moist (not muddy). Repeat weekly.
- Mist the enclosure daily. (I prefer using a pressure sprayer like this one made by Exo Terra so my hand doesn’t get tired.)
- Provide a warm humid hide lined with damp sphagnum moss. Humidity in this hide will get between 80-90% — a perfect retreat when your tegu is in shed.
Keep track of your humidity levels with a digital hygrometer— ideally, two of them: one for the warm side (which will be drier), and one for the cool side (which will be wetter). I like the Zilla Digital Thermometer/Hygrometer because it also gives me ambient temperature readings for that area.
Tegus also like having a personal “pool” large enough for their entire body and tail to fit inside, but no deeper than shoulder height. This is especially important for keeping Colombian tegus, and can be accomplished with a lightweight but durable Rubbermaid tub.
PRO TIP: Tegus often poo in their water, so be prepared to clean and replace daily!