Tegu Humidity, Lighting & Heating Requirements

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Tegu Lighting

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. In a 8′ long and 4′ tall enclosure with adequately deep substrate, you will need the 46″ Arcadia HO T5 12% lamp or Zoo Med T5 HO Reptisun 10.0 installed on the ceiling, with a basking platform 18-24″ below the bulb to help your tegu get the UVB it needs at that distance.

Installing UVB and making sure that your reptile is getting enough can be tricky with large enclosures. According to Dr. Frances Baines’ UV Tool, Salvator merianae (black and white tegus) are categorized under Ferguson Zone 3 as open or partial sun baskers. Assuming this applies to other tegu species as well, the all-day average UVI for these lizards is between 2.6-1.0, requiring a gradient from about 2.6 in the basking area to 0 on the other side of the enclosure. You will need a Solarmeter 6.5 to measure the precise UVI in your enclosure and make sure that your tegu is getting the right amount.

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.

Other Lighting

It takes a lot to light a large enclosure, and a heat bulb or two, plus a UVB bulb, isn’t going to be enough to provide the bright light that a diurnal reptile needs for simulating natural sunlight.

The brightest reptile light fixture currently on the market is the Arcadia Jungle Dawn LED Bar. They’re expensive, but the sheer output of bright, beautifully white light makes them worth the investment. I highly recommend installing one or even two in your tegu’s enclosure. The Arcadia LED Bar can be found in the US at either Light Your Reptiles or Reptile Basics. Use this to actively light at least half the length of your enclosure.

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 surface — 125-135°F (52-57°C)
  • Warm side — 90-95°F (32-35°C)
  • Cool side — 75-85°F (24-29°C)

Make sure to turn off all lighting and heat sources at night to create a nightly drop in temperature. This facilitates your tegu’s best health.

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 single 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 halogen flood lights clustered together, creating a proportionally larger basking zone.

This will take some careful experimentation to get right. We recommend using Philips PAR38 halogen heat bulbs and Lutron dimmer switches to accomplish this.

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 and Temperature Requirements

“Teddy The Tegu @ OSC” by Michael King is licensed under CC BY 2.0

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 from Exo Terra so my hand doesn’t get tired.)
  • Provide a cool humid hide box lined with damp sphagnum moss. Humidity levels in this hide should stay between 90-100%, with the moss replaced regularly to prevent mold.

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 Zoo Med 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!

Keep reading:

  1. Introduction to Tegus
  2. Shopping List
  3. List of Tegu Species
  4. Terrarium Sizing for Hatchlings, Juveniles & Adults
  5. Temperature & Humidity Requirements
  6. Substrate Options
  7. Decorating Your Tegu’s Enclosure
  8. Feeding Your Tegu
  9. Handling Tips
  10. Benefits of Free-Roaming
  11. Common Problems & Questions About Tegu Health
  12. Additional Resources