Nile monitors (Varanus niloticus) are 5-7’ long, diurnal, semi-aquatic lizards native to most of sub-saharan Africa. Where there is water, you are likely to find Nile monitors. They can be found in a wide variety of habitats, including swamps, mangroves, rivers, lakes, and pans. Aside from being strong swimmers, however, they are also strong climbers.

Nile monitors have a primarily black or gray base color with yellow or white spots. They have long necks, powerfully-built bodies and limbs, and long, laterally-compressed tails. Like other monitors, they have a long, forked tongue that darts in and out to gather information about their environment.

Although Nile monitors start out as cute, engaging babies, they quickly grow into huge, demanding, and potentially dangerous adults. They require a significant commitment in terms of space, cost, and care, making them an appropriate pet for only the most serious reptile keepers. With good care, they can live up to 20 years.

How much space do Nile monitors need?

Because they are huge, semi-aquatic, and spend a significant amount of time climbing, a single Nile monitor should be housed in no smaller than a 12’L x 12’W x 8’H enclosure (in other words, it needs a small room of its own). If at all possible, larger is strongly recommended. This size of enclosure is not typically available for purchase, so you will need to order one custom-made or build your own. If your local climate allows for an outdoor enclosure, it is best to house this species outside.

Cohabitation (keeping multiple Nile monitors in the same enclosure) is not recommended.

Do Nile monitors need UVB?

Yes! UVB is required for Nile monitors to thrive in captivity. Aside from helping provide a day/night cycle and providing an infinite supply of vitamin D, UVB is also good for the lizard’s overall health. Nile monitors prefer a partial sun habitat, so you will need a moderate-intensity, high-quality source of UVB as part of the enclosure. Here are the best UVB bulbs for Nile monitors housed in a 12’L x 12’W x 8’H enclosure:

• Arcadia Desert 14%, 34” (x4)

The UVB bulbs should be housed in a reflective fixture(s) in a 2x2 array and placed on the basking side along with the heat lamps. Make sure that the fixture your UVB bulbs are housed in does not have a clear plastic bulb cover. Because multiple UVB bulbs are required to create a large enough basking area, you will need a Solarmeter 6.5 to make sure that your monitor is getting a basking UVI of 3.0-4.0.

Since Nile monitors are active during the day and must be housed in a large enclosure, 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. Use at least 8’ of multiple, strong 6500K LED or T5 HO fluorescent plant grow lights for best results.

Sync your monitor’s day/night schedule with local sunrise and sunset times. This simulates natural seasonal changes in day length and encourages healthier hormonal rhythms.

Artificial UVB or other lighting is not necessary for Nile monitors housed outdoors as long as they have access to direct sunlight.

What basking temperatures do Nile monitors need?

Nile monitors need a basking surface temperature of 110-130°F and a warm side air temperature of roughly 88-92°F. The basking surface should be a stone or concrete platform large enough to accommodate the lizard’s entire body. 

Air temperature on the cool side of the enclosure can be as low as 72°F, but should be no higher than 80°F. Measure surface temperature with an industrial infrared thermometer (“temp gun”), and air temperature with a wall-mounted digital thermometer placed near the basking site. 

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 Nile monitor’s body. Do not use ceramic heat emitters (CHEs), heat mats, red bulbs, or blue bulbs, as these are not as effective.

Turn off light-producing heat sources at night. If the enclosure gets cold at night, use radiant heat paneling with a thermostat to maintain appropriate cool temps.

What humidity levels do Nile monitors need?

Nile monitors are a tropical species that needs a humid environment to stay healthy. Average humidity levels should be between 50-75%. Humidity should be measured with at least one wall-mounted digital hygrometer. Daily misting with an automatic misting system 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.

Because Nile monitors are semi-aquatic, they need more than just humid air — they also need a pool of water. At very least, the pool needs to be large enough for them to completely submerge (at least 12” deep). Ideally, it should be deeper and large enough to permit swimming.

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. Alternatively, you can build a drain into the pool and connect it to your property’s plumbing.

What substrate is good for Nile monitors?

Using substrate in your Nile monitor’s enclosure cushions your pet’s large body, encourages better posture, helps maintain humidity, and gives the lizard something to dig around in. This also means that it helps keep their nails filed down.

We recommend the following substrates for Nile 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 12” deep and completely replaced every 3-4 months. Remove poop and urates daily, along with any contaminated substrate. Removed substrate should be replaced immediately.

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

Nile monitors are highly intelligent and active animals, so it’s terribly boring for them to be stuck in an enclosure with nothing in it except substrate, a pool, and a basking platform. 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/ledges
• hollow logs
• tree stumps
• hiding places (dog houses/crates 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 Nile monitors eat?

Nile 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. Offer food every 1-2 days, in a portion roughly equivalent to the size of the monitor’s skull. Beware of feeding too much or too often as this leads to obesity.

When they’re young and small, they primarily eat insects like: 

• mealworms
• superworms
• dubia roaches
• discoid roaches
• hissing cockroaches
• grasshoppers
• hornworms
• earthworms 

When they’re older and larger, they switch to a vertebrate-based diet, although they also eat significant quantities of whole mollusks like captive-bred snails. Here are some ideas to maintain variety: 

• rats
• Mice
• rabbits
• guinea pigs
• chickens
• quail
• crawfish
• shrimp
• whole fish (tilapia, salmon, pollock)
• eggs

Supplements

You will also need calcium and vitamin supplements to prevent your lizard from developing a deficiency when it’s young. We recommend Repashy Calcium Plus LoD, lightly dusted on all insects. When the monitor is older and eating a whole prey diet, less frequent supplementation can be helpful for filling nutritional gaps.

Do Nile monitors like to be handled?

Truthfully, few reptiles actually “like” to be handled. Some Nile monitors tolerate handling and interacting with humans well, while others remain highly defensive after puberty and prefer to be left alone. It is important to be cautious and to learn how to read a Nile monitor, as their teeth, claws, and tail can inflict moderate to severe injuries on a human.

The key to building a trusting relationship with your Nile monitor is to provide as many positive interactions as possible. Offering food from feeding tweezers works well as an initial bribe. Designing enrichment activities is also a good way to engage your Nile monitor.

Always let the lizard come to you — never grab it! However, keep in mind that Nile monitors very rarely become “dog tame” like some other monitors.