Dumeril’s monitors (Varanus dumerili) are large, arboreal lizards native to southeast Asia, namely Thailand, Malaysia, Sumatra, Borneo, and nearby islands. They prefer to live near water, usually in a forested environment.

Dumeril’s monitors typically grow to a total length of 3.5-4’ long, although larger have been reported. They have a long head and neck, nostrils placed close to the eyes, a slender body, prominent round scales on the back and nape of the neck, and a laterally-compressed tail. After their first 4-8 weeks of life, Dumeril’s monitors develop brown and tan banded adult coloring.

Dumeril’s monitors are known to have a fairly docile temperament, and usually tame down well, especially when acquired as captive-bred juveniles. However, their housing and dietary requirements make them at least intermediate-level pets. With good care, Dumeril’s monitors should live for at least 10 years, and possibly up to 20+ years.

How much space do Dumeril’s monitors need?

Because of their size, a single Dumeril’s monitor should be housed in no smaller than an 8’L x 4’W x 6’H enclosure. If at all possible, larger is strongly recommended, in addition to regular opportunities to free-roam (supervised) for exercise. This size of enclosure is not typically available for purchase, so you will need to order one custom-made or build your own.

Cohabitation (keeping multiple Dumeril’s monitors in the same enclosure) is not recommended.

Do Dumeril’s monitors need UVB?

Although Dumeril’s monitors are known to be able to survive without it as long as they receive adequate vitamin D3 supplementation, we recommend providing UVB lighting to your new pet, as it is still required for them to thrive in captivity. Aside from helping provide a day/night cycle and providing an infinite supply of vitamin D, UVB provides other benefits that promote optimum wellbeing. 

Here are the best UVB bulbs for Dumeril’s monitors:

• Arcadia Desert 12%
• Zoo Med Reptisun T5 HO 10.0

The UVB bulb should be roughly half the length of the enclosure, mounted in a reflective fixture like Arcadia or Vivarium Electronics, and placed on the same size as the heat lamps. If the UVB is mounted over mesh, place the basking platform/branch so your monitor’s back will be 13-15” below the lamp. If the UVB is mounted inside the enclosure, place the basking branch so your monitor’s back will be 17-18” below the lamp.

Due to their equatorial origin, it’s best to provide 12 hours of light per day throughout the year.

Since Dumeril’s monitors are active during the day, it’s beneficial to provide an additional daylight-spectrum lamp to make sure the enclosure is brightly illuminated. This is extra important since you will be using such a large enclosure. Illuminate most of the enclosure with strong 6500K LED or T5 HO fluorescent plant grow lights for best results.

What basking temperatures do Dumeril’s monitors need?

Dumeril’s monitors need a basking area temperature of 110-120°F. Air temperature on the cool side of the enclosure should be between 80-85°F to create a temperature gradient for your monitor to control its body temperature with. Use at least two digital thermometers, one in the basking area and one in the cool zone.

Provide heat for your lizard by imitating the sun with a cluster of halogen heat lamps placed on one side of the enclosure. You will need enough lamps to evenly heat an area at least the size of the tegu’s body. Do not use ceramic heat emitters (CHEs), heat mats, red bulbs, or blue bulbs, as these are not as effective.

Heating should be turned off at night, with nighttime temps down to 68°F being appropriate.

What humidity levels do Dumeril’s monitors need?

Dumeril’s monitors are a tropical species that needs a humid environment to stay healthy. Average humidity levels should be maintained around 80%. Humidity should be measured with a digital probe hygrometer with the probe in the middle of the enclosure . Daily misting with a pressure sprayer and/or using a humidifier connected to a humidistat is helpful for maintaining high humidity. 

Reptile humidifiers and foggers should only be used with distilled water and require frequent disinfecting to keep your reptile from getting sick.

Dumeril’s monitors are arguably semi-aquatic, as they can submerge for up to 75 minutes at a time and have demonstrated the tendency in captivity to fall asleep in their water tubs. This means that your monitor will need more than just humid air — they also need a pool of water large enough for them to at least completely submerge. As a general rule, the pool area should be 1/2 to 1/3 the size of the enclosure.

Change out the water once weekly or whenever it gets soiled, and give the basin a good scrub with disinfectant before refilling. Using a siphon (or better yet, a mechanical water pump) and a hose will make emptying and refilling the pool much easier.

What substrate is good for Dumeril’s monitors?

Although Dumeril’s monitors spend a lot of time either climbing among branches or soaking in the water, they do occasionally hang out on the ground. Using substrate in your monitor’s enclosure will cover the floor and help provide a cushion in the unlikely event that it falls from its perch, but it also helps maintain humidity and gives the lizard something to dig around in.

We recommend the following substrates for Dumeril’s monitors:

• Zoo Med Eco Earth
• Zoo Med ReptiSoil
• Exo Terra Plantation Soil
• Zilla Jungle Mix

Layering clean, chemical-free leaf litter on top of the substrate can help with humidity as well as add enrichment value.

Substrate should be at least 4” deep and completely replaced every 3-4 months. Remove poop and urates daily, along with any contaminated substrate.

What décor can you use in a Dumeril’s monitor enclosure?

Dumeril’s monitors are highly intelligent and curious animals, so it’s terribly boring for them to be stuck in an enclosure with nothing in it except substrate, a pool, and a branch. It doesn’t matter how big the enclosure is if you don’t put things in it for your pet to use and interact with. 

At bare minimum, you will need a sturdy basking branch, swimming pool, somewhere to hide, and a thick layer of substrate. However, it’s best to include other items, such as:

• additional climbing branches
• raised platforms
• hollow logs
• tree stumps
• additional hiding places (dog/cat kennels can work well)
• live or artificial foliage

All climbing branches should be securely anchored into the walls/floor of the enclosure to prevent collapse.

What do Dumeril’s monitors eat?

Dumeril’s monitors are carnivores, which means that they need to eat a variety of animal-based foods in order to get the nutrition that their bodies need. How often they need to eat depends on age: Hatchlings and juveniles should be fed daily to every other day for older individuals, but once they near adulthood, reduce feedings to 3-4x/week. Each meal should be slightly smaller than the lizard’s skull.

The key to providing a healthy, balanced diet for your Dumeril’s monitor is VARIETY. Here are foods that are appropriate for your pet to eat:

• snails (captive-bred only)
• mealworms
• superworms
• dubia roaches
• grasshoppers
• hornworms
• crawfish
• crabs
• shrimp
• whole fish (tilapia, salmon, pollock)
• frogs
• frozen rodents
• eggs

Young Dumeril’s monitors are more likely to be interested in insects than adults.

Supplements

You will also need calcium and vitamin supplements to help prevent your lizard from developing a deficiency. We recommend Repashy Calcium Plus LoD, lightly dusted on all foods (excluding whole prey).

Do Dumeril’s monitors like to be handled?

Truthfully, few reptiles actually “like” to be handled. But when it comes to Dumeril’s monitors, they usually tame down well enough to tolerate and possibly even seek out human interaction. The key to building a trusting relationship with your pet is to provide as many positive interactions as possible. Offering food from feeding tweezers works well as an initial bribe, and it’s best to get the monitor to come to you rather than simply grabbing it.

When you start handling your Dumeril’s monitor, be gentle. Don’t grab the lizard from above — instead, approach from the side and scoop from below. Support as much of its body as possible, especially its feet. Start with very short handling sessions in the beginning, then gradually make them longer as your pet becomes more accustomed to you.