Asian water monitors (Varanus salvator) are truly majestic and intelligent lizard giants, earning them a loyal following in the reptile trade. This species hails from southern and Southeast Asia, where they’ve evolved over millions of years to survive in both wild and urban settings through their many adaptations. While their husbandry requirements can be challenging, many hobbyists are rising to the challenge and discovering how truly rewarding it is to share your home with an “Urban Dinosaur.” Keepers are also experiencing the true social and intellectual capacity of these lizards, guided by their extreme intelligence and ability to form bonds. Here we hope to contribute to quality husbandry with reptile supply recommendations and tips. In recent years captive breeding has expanded, bringing to the market a range of unique specimens both in personality and appearance. Captive breeding has allowed us to pair the hallmark of a tame manageable monitor with the undeniable beauty of morphs and selective breeding, making them one of the most impressive and rewarding animals available to keepers. Observing these animals in their native range is further evidence of their incredible ability to not only survive, but thrive in varying and often difficult environments.
The Asian Water Monitor’s Natural Range
The vast range of water monitors is a testament to their remarkable ability to adapt. They’re found as far north as Northeast India and all the way down to the insular regions of Southeast Asia. Within these regions, they have proven to flourish in a variety of landscapes throughout this range, including urban settings such as the metropolis of Bangkok, Thailand! Although Varanus salvator are considered a lowland species, they have been found at elevations as high as nearly 6000 feet above sea level. This species is harvested in large numbers for their leather, body parts and meat throughout much of their range. The successful expansion of this semi-aquatic lizard can be credited to many of their unique adaptations, including their intelligence and size.
Asian Water Monitor Size/Description
Asian water monitors are regarded as the third longest lizard after the komodo dragon (Varanus komodoensis) and the crocodile monitor (Varanus salvadorii). The longest water monitor on record was a specimen from Sri Lanka measuring an impressive 10.5 feet long! They have a truly astounding growth rate, even seasoned keepers are still surprised at the gains these animals can make in a short period. Hatchlings will start out at about 10 inches long and will potentially grow several feet in a single year under optimal conditions. Ultimately, the adult size of a water monitor depends on several factors including their genetics, locality, diet, and husbandry parameters. Being a sexually dimorphic species, males typically dwarf females and will range from 5-8 feet once full grown. Females are considerably smaller, normally maxing out at approximately 4-6 feet. There are certainly cases where water monitors have surpassed this size, but such cases are considered exceptional. Along with their large size, water monitors have a life expectancy of at least 15 years, possibly up to 20+ years in captivity due to modern advances in reptile keeping. Housing an animal that can attain this large size can pose a challenge. Fortunately, there are many enclosure options available to keepers.
Reptile Heating & Lighting
Properly heated monitors should bask for a limited time, then explore their enclosure before returning to the basking area, a true example of thermoregulation. This cycle should be repeated throughout the day. If a monitor is spending an inordinate amount of time basking, then the basking and/or ambient temperatures may be too low. Conversely, if a monitor lizard is never basking then this may be because temperatures are too high. Correct temperatures in conjunction with correct humidity are two significant factors in maintaining a happy, healthy animal. Basking is extraordinarily important for all monitor lizards as they are dependent on external heating to help regulate their metabolism. The temperature of the basking surface area should fall in the range of 125-140º F. Floodlights are often the basking bulbs of choice since they generally achieve higher temperatures at lower wattages over a larger surface area compared to conventional basking bulbs. Placing numerous bulbs in a bank positioned parallel to one another is best for larger monitors to adequately heat the entire animal during basking. This will help avoid burns as the monitor will be able to achieve their ideal temperature in a reasonable time period. Monitors must be provided a cooler area as well, where the reptile can retreat to cool down, as this is critical during digestion where body temperatures can rise due to metabolic activity. Water monitors generally reside in regions close to the equator where temperatures typically do not fluctuate significantly throughout the year. Therefore, ambient temperatures in their enclosures should be maintained in the low to mid 80º Fs. Although temperatures can be allowed to drop slightly at night within reason, many keepers perpetually maintain conditions constant with great results. When adequate temperatures are combined with a large water reservoir, the humidity levels in the enclosure will rise.
Proper Humidity for Your Asian Water Monitor
Varanus salvator relish the water and normally are found near bodies of water such as mangrove swamps in the wild. Captive water monitors require a water reservoir large enough for them to fully submerge in. The cleanup associated with water monitors is directly correlated to water changes since monitors will often urinate and defecate in the water. Therefore, once the water is replaced the majority of cleanup is completed. Daily water changes are recommended unless strong filtration is set up. Humidity levels around 60 to 70 percent are perfect as overly humid conditions can lead to health issues like scale infections. Stale wet air can lead to fungal and bacterial lesions that can overcome the animal’s immune response. There are many commercially available thermometers and hygrometers on the market to record temperature and humidity accurately. Practicing proper husbandry is of the utmost importance for all animals. Unfortunately, some hobbyists do not anticipate the care requirements of large lizards and some water monitors are surrendered and rehomed as adults. This is why it is important to be prepared for the commitment of keeping a large carnivore that will require a lot of space and food.
Asian Water Monitor Diet
Large lizards have huge appetites! It’s recommended that hatchling water monitors are fed daily to every other day for their first year of life. This will be the period of time when the most growth occurs and the diet needs to provide the necessary nourishment for extreme growth. A well-fed lizard may not be interested in feeding for a few days while smaller frequent feedings may yield a constant appetite. Baby monitors tend to be highly insectivorous and their captive diets should reflect this; a diet comprised primarily of gut loaded crickets and varying species of roaches are a good choice. In addition to gut loading, it is also important that insects are dusted with acalcium/Vitamin D3 supplement before being offered to the lizard. This is important to add to your lizard food.Growing monitors can gradually be transitioned to whole prey items, such as appropriately sized rodents, fish, and poultry. Yearling monitors can be fed whole prey items about three to four times weekly, while full size adults over two years old can be fed less frequently, typically two to three times weekly. It is important to remember that water monitors are opportunistic feeders and will rarely refuse a meal. This voracious appetite means adult water monitors are prone to obesity in captivity and that can result in a host of health issues, ultimately resulting in a shortened life expectancy. After a meal, monitors will bask to help digest their food, so again it is important to ensure your enclosure has proper temperatures and ample basking area.
Choosing a Water Monitor
Once your enclosure is set up and you are prepared for the task of feeding your urban dinosaur, it’s time to choose your water monitor. A captive-bred specimen is always recommended over a wild-caught animal, as they will be socialized much more easily without the trauma of capture and export. Monitor lizards hand raised in captivity also tend to be more innately tractable and well-socialized when provided with proper care. There’s also health risks with wild-caught animals, such as parasites or foreign contaminants. Acquiring a healthy water monitor is of the utmost importance. When you choose your animal there are a few tips that can assist you in choosing a healthy specimen: You should choose an animal that appears robust and active, with open clear eyes and no excessive secretions from the nose or mouth. Keep in mind that an inactive animal may appear more “friendly,” but this lack of vigor could potentially indicate health issues. There are currently some reputable breeders of Varanus salvator, making acquisition of a healthy, hand-raised specimen practical for all expert keepers. Maintaining a healthy animal will of course significantly reduce stress for both keepers and their clever monitors.
Socializing Asian Water Monitors
Intelligence is undoubtedly a hallmark of the monitor lizard; millions of years of evolution has armed water monitors with the intelligence to adapt and survive in a myriad of environments. In captivity, this extreme intelligence has allowed keepers to socialize our animals and establish relationships that previously weren’t considered possible.
Incubating Asian Water Monitor Eggs
Depending on the age and size of the female, clutches range between six to 18 eggs, although more or less is not uncommon. There must be deep substrate of proper composition and consistency present in order to increase the likelihood of successful nesting. Females prefer their nesting site substrate at 86ºF, and will spend several days digging “test holes” until she finds a suitable nesting location. In a correctly maintained enclosure, meeting such requirements should be straightforward. Once the female has laid her clutch, the eggs are placed in a plastic container filled with hatchrite media and incubated at 86ºF. At this temperature babies will begin to hatch in six to seven months. Hatching baby water monitors is truly one of the most rewarding experiences as a reptile keeper.
The Future of Varanus salvator in Captivity
We’ve only begun to scratch the surface of the potential that water monitors possess. They have proven to be magnificent captives. Although their requirements may be a bit of a challenge, if you rise to the occasion, you will be rewarded with an intelligent and captivating reptile. Captive propagation has resulted in some of the most impressive color mutations available, and the future of combining these mutations is still ahead of us. As our understanding of water monitors grows, we will continue to see their popularity grow.