Monitor Lizards and Goannas as Pets

People usually land on a page like this with one practical question in mind: is a monitor lizard (goanna) a realistic pet for my home, my budget, and my experience level?

These reptiles can thrive in captivity, but they don’t forgive guesswork. Heat, UVB, space, and diet all carry consequences—poor settings often show up later as chronic illness, injuries, or a lizard that learns to treat hands as threats.

Monitor lizards and goannas: what they are (and what they aren’t)

“Goanna” is the common Australian name for several monitor lizards (genus Varanus). They’re alert, athletic predators with strong claws, sharp teeth, and a habit of testing boundaries—especially when cramped, underheated, or repeatedly handled when they’d rather be left alone.

They are not “social” pets in the way dogs, rats, or parrots are. Some individuals become calm around their keeper through steady, low-pressure routines, but that tolerance sits on top of good husbandry, not instead of it.

Quick reality check before you buy

• Space is non-negotiable. Even “small” monitors need large, secure enclosures with depth for digging and room for a proper heat gradient.
• Heat and UVB are foundational. Many serious health problems trace back to inadequate basking heat and UVB exposure.
• Feeding is messy and ongoing. Whole-prey and insects mean storage, hygiene, and reliable suppliers.
• Legalities apply. In Australia, keeping native reptiles typically requires licensing and legally sourced (captive-bred) animals, with rules varying by state/territory.

Size, lifespan, and long-term commitment

Monitors range from compact species under a metre total length to giants well over 2 metres. A perentie (Varanus giganteus), for example, is among Australia’s largest lizards and can exceed about 2.4 metres and reach roughly 18 kg in some reports—far beyond what most private keepers can house responsibly.⁶

Many commonly kept monitors can live well over a decade, and 15–20 years is a realistic timeframe for some species under good care.⁹

Choosing a species: start smaller, stay honest

The original draft mixed species and sizes in ways that don’t hold up. “Savannah monitors” aren’t Australian natives, and “shingleback” is a different kind of lizard entirely (a blue-tongue), not a monitor.

If you want an Australian monitor that’s often considered more achievable in captivity, the spiny-tailed (Ackie) monitor (Varanus acanthurus) is commonly cited at roughly 60–70 cm total length, with a long lifespan and very high heat requirements despite its smaller size.⁷

Whatever species you’re considering, check:

• adult size (not juvenile size in a shop tub)
• activity level and digging/climbing needs
• whether it’s on your state’s “allowed species” list
• the enclosure you can provide now, not “after an upgrade”

Housing and enclosure requirements

A monitor enclosure should feel like a landscape, not a box. You’re aiming for safe movement, choice of microclimates, and strong containment.

Core enclosure features

• Secure, escape-resistant build (monitors push, pry, and climb with purpose).
• Thermal gradient with a genuinely hot basking site and cooler retreats.
• UVB lighting appropriate to the species and enclosure height.
• Deep substrate for species that burrow (many do), plus stable hides.
• Water access suited to the species (some drink readily; some also soak).

Cleanliness matters, but so does stability. Over-scrubbing and constant “resetting” can remove scent cues and increase stress; aim for regular spot-cleaning and planned deep cleans, keeping the enclosure layout mostly consistent.

Feeding and nutrition (including feeding mice)

The draft described monitors as “omnivorous” with daily vegetables, which is too broad. Many goannas are primarily carnivorous and opportunistic, eating what they can catch and swallow—often insects, eggs, and small vertebrates, depending on the species and size.⁵

What a sensible captive diet usually looks like

• Insects as a staple for smaller species and juveniles (roach species, crickets, and other well-fed insects).
• Whole-prey items (such as appropriately sized rodents) used carefully—more often as part of rotation than an everyday default for many species.
• Calcium and vitamin strategy matched to the species, age, and lighting setup.

Feeding mice: common mistakes to avoid

• Too large, too often. Frequent oversized rodents can drive obesity and poor overall balance. Size prey appropriately.
• Using rodents to replace insects. Many smaller monitors do best with insect-heavy diets rather than rodent-heavy routines.
• Hygiene shortcuts. Keep frozen feeders properly stored, thaw safely, and remove uneaten food promptly to prevent spoilage and pest problems.

How often to feed

“Daily” is not a universal rule. Frequency varies with species, age, body condition, and temperature. Fast-growing juveniles often eat more frequently than adults; many adults do better on a spaced schedule that maintains lean muscle rather than constant surplus.

Handling and “taming”: keep it low-pressure

Monitors can become steady around a familiar keeper, but it’s more accurate to think in terms of habituation and trust through predictability than “training”.

Good handling is mostly about what you don’t do:

• don’t grab from above like a predator
• don’t corner the lizard in the enclosure
• don’t force interaction on feeding days
• don’t keep handling if the animal escalates (hissing, whipping, repeated fleeing)

Health concerns and veterinary care

Captive monitors commonly run into trouble when the basics are slightly off for a long time: inadequate UVB, insufficient basking heat, poor supplementation, and chronic dehydration or low humidity where a species needs more. One well-known outcome is metabolic bone disease, which is strongly linked to calcium imbalance and insufficient UVB (needed for vitamin D3 synthesis and calcium use).⁸

Find an experienced reptile veterinarian before you buy. Early advice—based on your actual enclosure temperatures, UVB type/placement, and diet—can prevent expensive emergencies later.

Behavioural issues you’re likely to see (and what they usually mean)

Most “behaviour problems” are husbandry problems in disguise.

• Persistent hiding can point to stress, inadequate heat, or lack of secure retreats.
• Defensive displays (hissing, tail whipping, lunging) often follow repeated unwanted handling or feeling exposed.
• Food obsession can happen when diets are too fatty or routine is too predictable (the lizard learns that hands equal food).
• Glass surfing/pacing can reflect boredom, insufficient space, or temperatures that don’t allow comfortable thermoregulation.

Legal requirements in Australia (don’t skip this)

Rules vary by state and territory, but the theme is consistent: native reptiles are protected, and keeping them generally requires a licence and legal sourcing from licensed breeders or dealers. In NSW, for example, you need a biodiversity conservation licence to keep native reptiles, and you must obtain animals through lawful channels rather than taking them from the wild.^{1, 4}

Before committing, check the requirements where you live and confirm the species is permitted under your licence class.^{1, 2}

Final thoughts

A monitor lizard can be an extraordinary animal to keep—watchful, precise, endlessly physical—when its enclosure is built around heat, light, space, and routine. Without those, they tend to unravel slowly: poor appetite, brittle bones, chronic infections, and an animal that survives rather than lives.

Choose a species you can house at adult size, set the enclosure up first, and treat handling as optional, not the goal.

References

1. NSW Environment & Heritage (DCCEEW): Reptile keeper licences
2. Service NSW: Apply for a native animal keeper licence
3. NSW Environment & Heritage (DCCEEW): Apply for a native animal keeper licence (fees and licence classes)
4. NSW Environment & Heritage (DCCEEW): Buying and caring for native reptiles
5. Bush Heritage Australia: Goannas (Monitor Lizards)
6. Associated Press: LA Zoo hatches first-ever perentie lizards (includes adult size/weight figures)
7. Wikipedia: Spiny-tailed monitor (Varanus acanthurus) (overview and reported adult length)
8. Vetafarm: Metabolic bone disease in lizards (UVB, calcium, and treatment overview)
9. Swell Reptiles: Ackie monitor care sheet (lifespan and general husbandry parameters)