Monitor lizards are popular pet lizards because of their dynamic personalities, interesting anatomy and physiology, and variable size. There are more than 70 species of monitor lizards in the world, ranging from about one foot in length for the dwarf species up to 10 feet in length for the Komodo dragon (Varanus komodoensis). These lizards are highly adapted in their different environments, easily moving between terrestrial, arboreal, and aquatic systems. It is important to always learn about the life history and needs of any pet reptile to ensure they have what they need. Here, we will provide some basic information on monitor lizards to get you started.
By doing your homework ahead of time, you will ensure that you will have the best habitat and nutrition prepared for your monitor lizard before their arrival at your home.
Quick facts
- Monitor lizards are native to Africa, Asia, and Oceania.
- Male monitor lizards are typically larger than females and have obvious hemipenal bulges in the base of their tail.
- Monitor lizards are ectotherms and depend on environmental temperatures to regulate their core body temperature.
- Monitor lizards can be found in arboreal, terrestrial, or aquatic habitats.
- Monitor lizards are carnivores.
- With appropriate care, monitor lizards can live for 10-20 years.
Enclosure
Monitor lizards should be provided with the largest enclosure possible to ensure they have ample room to hunt and exercise. Juvenile monitor lizards can be housed in glass tanks or reptile specific commercial enclosures; however, as some species grow, they may require purpose-built enclosures because of their large size. It is important to research the specific needs of your monitor lizard. Terrestrial species will need enclosure with a larger width and length, while arboreal species require more vertical height in the enclosure.
The type of material used for the enclosure is an important consideration for disinfection. This is generally not a major concern for glass tanks or commercially made reptile enclosures but can be an issue for home-made/purpose-built enclosures made of wood. Because wood is difficult to disinfect, it is not recommended as building material for an enclosure.
Substrate
There are a number of different substrates that can be used for monitor lizards, including astroturf/green carpet, recycled paper substrates, and different types of wood substrate (e.g., cypress, aspen). The astroturf/green carpet substrate is good after first acquiring a monitor lizard to evaluate its feces, or to use in separate smaller enclosures as a feeding station. The recycled paper is good because it is easy to clean and does not produce dust. While wood mulches are aesthetic, they can impact the humidity in the enclosure. The substrates should be spot cleaned daily to remove waste and changed regularly (based on type and how soiled they become).
Accessories
Monitor lizards should be provided with ample branches for climbing. Different sized and textured (bark, no bark) branches are important to use because they provide the lizard with different surfaces to grasp. This allows them to “exercise” their toes (digits) and remove shed on the bottom of the feet. Having some branches under a heating lamp or ultraviolet B light will provide basking areas for the monitor lizard.
Weighted food and water bowls should be provided. The weighted bowls will reduce the likelihood of the monitor lizard tipping over the bowls. The bowls should be large enough for the lizards to soak, but not too deep, especially for juvenile animals, to prevent drowning. Fresh water should be provided daily.
Temperature and Lighting
Monitor lizards should be provided with supplemental environmental heat to ensure they can meet their needs. As poikilotherms or ectotherms, they depend on their environmental temperature to regulate their core temperature. For monitor lizards, heat can be provided using a basking lamp or under tank heating pad. A basking lamp should be situated over one side of the enclosure to provide a gradient of temperature. The daytime temperature range for monitor lizards should be 82-88oF. By having a gradient of temperatures, the lizard can move from warmer to cooler temperatures based on its preference. The nighttime enclosure temperature can drop by 10oF; this is often achieved simply by turning off the heat lamp. The under-tank heating pad can be used in places where nighttime environmental temperatures drop below 68-70oF. The environmental humidity for monitor lizards should be 60-80%.
An ultraviolet B (UVB) bulb would also be beneficial for monitor lizards. These bulbs can help diurnal reptiles increase their vitamin D concentrations. Vitamin D is an essential hormone that regulates bone health, immune function, and heart health, among other factors.
Monitor lizards should be exposed to basking and UVB lighting for 12 and 2 hours per day, respectively.
Diet and Nutrition
Monitor lizards are carnivores, and like us, diversity in their diet is the key to providing them with balanced nutrition. For juvenile monitor lizards, providing a variety of live gut-loaded insects using Fluker Farms specific gut-loading diets for crickets, mealworms, and dubia roaches will ensure their diet has sufficient calcium (positive calcium to phosphorus ratio). As the animals age, they should be offered whole prey such as mice, rats, quail, and/or fish; these selections are often based on their natural life history.
Juvenile monitor lizards should be fed daily, but as they age that can be altered to every other day to 2-3 times per week. Because monitor lizards don’t get much exercise in captivity, they can become too heavy if they are fed daily. Smaller meals that they must search for can increase their daily exercise.
Handling and Safety
Monitor lizards can become gentle with handling. For juvenile monitor lizards, gentle restraint in one hand by wrapping your fingers around their abdomen and rear legs is generally sufficient, whereas for larger animals it is best to support their body and tail base. Monitor lizards tend to want to always move forward and climb, so be sure they don’t fall and injure themselves. The nails of monitor lizards are used to gain traction for running and climbing, so they are sharp. The tips can be trimmed (just the point) to reduce the risk of scratching. When alarmed, monitor lizards will also use their tail to whip a perceived threat. Finally, monitor lizards can inflict a nasty bite, so care should be taken not to alarm the lizard.
Because monitor lizards can carry Salmonella, it is important to thoroughly wash your hands after handling these animals or their enclosure. Children should always be supervised when handling any reptile and observed closely to ensure they thoroughly wash their hands after handling the lizard or anything associated with their enclosure.
Contact a veterinarian if you notice any signs of illness or distress, such as more time spent hiding in the cage, eating less, weight loss, swollen joints, discharge from the eyes or nose, or abnormal feces.
Shopping List 
- Diet- Crafted Cuisine- Garden Diet
- Freeze-dried bugs
- Live bugs
- UVB lighting
- Heat lamps
- Thermometer/hygrometer