Reptiles
Ackie Monitor
Varanus acanthurus
Intelligent, active dwarf monitorAdvanced
- Lifespan
- 15-20 years
- Size
- 60-75cm (24-30in)
- Social needs
- Solitary or carefully managed pairs
- Time
- High - daily feeding, enrichment
- Cost
- High
- Diet
- Insectivore/carnivore - insects, rodents
Overview
What is this animal?
- Ackie monitors, or spiny-tailed monitors, are small Australian dwarf monitors valued for their intelligence and activity.
- Though small for a monitor, they are demanding lizards that need far more than typical reptile husbandry.
- They are alert, fast, and curious, displaying complex behaviours such as digging, climbing, and problem-solving.
- They suit dedicated, experienced keepers able to provide a large, high-heat, enrichment-rich enclosure.
Temperament
- Ackies are intelligent and can become tame and interactive with consistent, patient handling, often recognising their keeper.
- However, they are fast, strong for their size, and can scratch or bite if stressed.
- They are best regarded as active, engaging display animals that may accept handling rather than as cuddly pets.
- Their inquisitive nature rewards enrichment and routine, but they need an experienced, committed keeper.
A good fit for
- Experienced, dedicated reptile keepers
- Those able to build a large high-heat setup
- Keepers wanting an intelligent, active monitor
- People committed to daily enrichment
Common mistakes to avoid
- Needs very high basking temps (50-60C)
- Deep burrowing substrate is essential
- Large enclosure and high cost often underestimated
- Not a beginner reptile despite small size
Enclosure
Minimum 16,200 cm² of floor (2,511 sq in) · 180 × 90 × 90 cm
Fine alone or with company. Solitary or carefully managed pairs
- Ackies need a large enclosure, at least 180x90x90cm and ideally bigger, with a deep substrate of around 30-60cm of a moisture-holding sand-soil mix that holds burrows.
- Floor space and burrow depth are critical.
- They require an intense basking zone of 50-60C surface temperature under a focused basking lamp, with a cool retreat around 24-28C, plus strong UVB.
- This high-energy thermoregulation is essential to their digestion and health.
Supplies
Setup
- Enclosure
- Heating and thermostat
- UVB fixture and bulb
- Thermometers and hygrometer
- Substrate and decor
Ongoing
- Live dubia roaches, crickets and locusts in bulk
- Frozen rodents for occasional feeding
- Plain calcium powder without D3
- Calcium with D3 and a reptile multivitamin
- Feeder gut-load and a large ventilated feeder tub
- Long blunt-tipped feeding tongs
- Heavy, tip-proof water dish
- Digital scale for tracking body weight
Safe substrate: Topsoil and play sand mix · Coco fibre and coir · Cypress mulch
Care routine
Daily
- Check the basking surface temperature
- Fresh water bowl
- Look the animal over
- Spot-clean waste and uneaten food
Weekly
- Feed a varied, portion-controlled dietevery 2 days
- Short handling sessionevery 3 days
- Check the substrate holds a burrow
Monthly
- Weigh-inevery 2 weeks
- Deep-clean the enclosure
- Test thermostats, lamps and guards
Less often
- Refresh the substrateevery 3 months
- Replace the UVB lampevery 6 months
Vet: Annual exam and faecal check — every 12 months (every 6 months from 10 years old)
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
YouTubers
Reptiles and ResearchEvidence-led husbandry: enclosure size, UVB, thermal gradients, enrichmentClint's ReptilesWhich reptile suits you, with honest care and handling verdictsGoHerpingBeginner reptile care, setup mistakes and welfare basics
Sites
Go deeper
Diet
- Ackies are insectivores and carnivores fed a varied diet of appropriately sized insects such as roaches, crickets, and locusts, with the occasional whole rodent or egg.
- Gut-load and dust insects with calcium and vitamins.
- Juveniles eat daily and grow fast; adults are fed several times a week.
- They are prone to obesity on fatty prey, so monitor body condition and favour lean, varied invertebrates over frequent rodents.
Health
- Ackies suffer when kept too cool or without high enough basking temperatures, leading to poor digestion and obesity.
- Inadequate UVB and calcium cause metabolic bone disease, and shallow, dry substrate prevents natural burrowing and thermoregulation.
- Provide intense heat, strong UVB, deep moisture-holding substrate, and a varied diet.
- Their high metabolism and activity demand careful temperature and weight management, with support from a monitor-experienced vet.
Is your enclosure big enough?
Minimum floor area16,200 cm² (2,511 sq in) of continuous, unbroken floor
As dimensions180 x 90 x 90 cm
CompanyFine alone or with company. Solitary or carefully managed pairs
Is this urgent?
Most reptile emergencies are husbandry emergencies first. Before you panic, check the temperatures — but check them with a thermometer, not a hand.
Go now
Open-mouth breathing, or bubbles and mucus at the nose or mouthGo now. Raise the warm end to the top of the species range in transit. Respiratory infection in a reptile is usually already established by the time it is visible, and it advances fast at the wrong temperature.
NowProlapse — any tissue protruding from the ventGo now. Keep the tissue moist with clean lukewarm water. Do not push it back in. Exposed tissue dries and dies quickly, and the window for a simple repair is short.
NowGaping, gasping, or unable to right itself when gently turned overGo now. Loss of the righting reflex signals a neurological or metabolic crisis.
NowA burn, or a blackened patch on the belly or sideGo now, and unplug the heat source before you leave. Contact burns from an unregulated mat or an unguarded lamp are among the most common injuries in captive reptiles.
NowToday
Tremors, twitching, jerky limbs, or a rubbery jawCall today. Note your UVB bulb type and when it was last replaced. Almost always a calcium and D3 problem, and almost always a UVB problem underneath that.
TodayRetained shed over the eyes, or a ring of stuck shed on the tail or a toeRaise humidity and offer a damp hide, then call if it is not clear within a day. A constricting ring cuts off circulation and the digit or tail tip is lost.
TodaySudden weight loss, or a visibly sunken or triangular body shapeCall today, with the weight history. A reptile that has lost condition has usually been unwell for a while.
TodaySoon
Refusing food beyond the species' normal fastCheck what a normal fast looks like for this species before worrying — for several snakes it is weeks, not days. Then log it and book if the fast is unusual for this animal. Feeding anxiety drives more unnecessary vet visits than any other reptile question, and also masks the fasts that genuinely matter.
Check the guide firstBefore any non-emergency call, write down the four numbers a vet will ask for: the thermostat probe reading, the warm-end air temperature, the cool-end air temperature, and the hottest accessible surface. Surface temperature can run well above the air above it.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
Can a ackie monitor eat that?
Reptile diets split hard by species. An insectivore and a grazing tortoise share almost nothing, so check the species guide as well as this list.
The full list
Never (15)
AlcoholNo safe amount at any body weight on this site.
neverAvocadoPersin. Fatal to many reptiles.
neverCaffeineCoffee, tea and energy drinks. Cardiac and neurological toxicity at tiny doses for an animal this size.
neverChocolateTheobromine and caffeine. Small mammals and reptiles cannot clear either.
neverCitrusToo acidic, and it interferes with calcium absorption.
neverDog or cat foodProtein and vitamin D levels formulated for a mammal. In tortoises it causes irreversible kidney and shell damage.
neverFirefliesLucibufagins. A single firefly has killed adult lizards. This is the most dangerous item on any reptile list and it is the one keepers do not know about.
neverFish caught from the wildThiaminase and parasite risk for turtles and aquatic species.
neverGarlicSame allium toxicity as onion, and more concentrated by weight.
neverIceberg lettuceWater with no nutrition. It fills a reptile up in place of food that would have done something.
neverLeekAllium family. Same mechanism as onion and garlic.
neverOnionOrganosulphur compounds damage red blood cells. The whole allium family is out.
neverRhubarbOxalate load high enough to cause acute kidney injury.
neverSalty or seasoned human foodSalt, oil and seasoning. Crisps, chips, seasoned leftovers and processed meat are all out.
neverWild-caught insectsPesticide residue and parasites, and the identification risk. Captive-bred feeders only.
neverRare treats (1)
WaxwormsVery fatty. Useful for a underweight animal or for medicating, addictive otherwise. One or two, rarely.
rare treatOccasional (5)
Bell pepperSafe, low oxalate, and the colour gets a refuser eating. A few small pieces a few times a week.
occasionalButternut squashWell tolerated and a useful source of vitamin A precursors. Small cubes a few times a week.
occasionalKaleGood calcium, mild goitrogen. Rotate it. Twice a week.
occasionalMealwormsHard chitin shell and a poor calcium ratio. Fine as part of a varied feed, poor as the whole diet. A few, alongside better feeders.
occasionalSpinachOxalates bind dietary calcium, which is the last thing a reptile at risk of metabolic bone disease needs. A very small amount, rarely.
occasionalEveryday foods (6)
Black soldier fly larvaeUnusually high in calcium; one of the few feeders that does not need dusting. Several per feed.
everyday foodCollard greensOne of the best staple greens for herbivorous and omnivorous reptiles. Daily.
everyday foodCricketsA standard feeder. Gut-load them for 24 hours before offering, or you are feeding an empty shell. Sized no wider than the space between the animal's eyes.
everyday foodDandelion greensExcellent calcium-to-phosphorus ratio and readily taken. Pick away from sprayed ground. Daily, for herbivorous species.
everyday foodDubia roachesBetter calcium ratio and more meat per insect than crickets, and they cannot climb glass. Sized to the animal.
everyday foodMustard greensGood calcium ratio; rotate with other greens. Several times a week.
everyday foodThat food is not on our list. Reptile diets are narrower than they look — check the species guide, and ask an exotics vet before offering anything unfamiliar.
Dust feeders with a calcium supplement to the schedule in the species guide. A reptile can be eating well and still be starving of calcium.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate choice follows the animal's natural humidity, not the look of the vivarium. Get that pairing right and most substrate arguments disappear.
Safe
Topsoil and play sand mixThe standard bioactive-ready base for arid and semi-arid species. Plain topsoil with no fertiliser, no perlite, no wetting agents.
safeCoco fibre and coirHolds humidity well for tropical species. Rinse and check it is not bone dry, which makes it dusty.
safeCypress mulchGood humidity retention for tropical snakes. Cypress specifically, not general 'wood mulch'.
safeOrchid barkLong-lasting, holds humidity, resists compaction. Common in tropical vivaria.
safePaper towel or newspaperNot attractive, but correct for quarantine, for a new arrival, and for any animal being monitored for output.
safeLeaf litter over a soil baseCover, humidity and invertebrate habitat in one. Sterilised, from a known source.
safeWith a caveat
Reptile carpetSnags claws and traps bacteria in the fibres. If used, it needs replacing rather than washing, often.
with a caveatSand alone for desert speciesReal desert is packed substrate, not loose play sand. Mix it with soil so it holds a burrow.
with a caveatBioactive setupsExcellent when established, but the clean-up crew needs weeks to establish before the animal goes in.
with a caveatNever
Calcium sand and 'digestible' sandsMarketed as safe to eat, which encourages eating it. Implicated in impaction.
neverCrushed walnut shellSharp fragments, frequently implicated in impaction, with no advantage over soil.
neverPine and cedarSame aromatic phenols as in rodent bedding, and the same airway damage.
neverUncovered heat mats and unguarded ceramic emittersNot a substrate, but the most common cause of contact burns. Every heat source needs a thermostat, and every emitter needs a guard.
neverThis is our general list for reptiles. We have not built one specific to Monitors yet.
Impaction is far more often a temperature problem than a substrate problem: an animal that cannot reach its digestive temperature will not pass what it swallows, whatever it is standing on.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
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