After meeting my first Ackie monitor, I was in love. This medium sized, active, extremely intelligent lizard is an absolute joy to own. It does have some more complicated care requirements than other species, which makes us put it in the intermediate range, but with today’s equipment and husbandry knowledge, caring for Ackie Monitors is easier than ever before, as long as you’re willing to do adequate research and are sure this is the right species for you. That’s where I come in – I’m going to be sharing information about this dwarf monitor, how you keep them, from housing, heating and lighting, to handling, social needs and diet. Read on!

If I miss anything, don’t hesitate to drop us a message on Facebook, email or leave a comment.

Meet the Ackie Monitor

The most common pet trade name for Varanus acanthurus is the Ackie monitor – shortened from the latin name. However you’ll also frequently see them referred to as the Dwarf Ridge Tailed Monitor, or Dwarf Spiny Tailed Monitor.

Adult Ackie Monitors

Although the name says “Dwarf”, this is not a small lizard, it’s simply small in terms of monitors, which is a group that includes some of the largest reptiles in the pet trade. Dwarf Ridge Tailed Monitors get to around 2ft when fully grown. In weight they weigh less than a Bearded Dragon, but they have different proportions, with a very small pointed head and a much longer tail – the tail makes up most of the total length. They are an extremely muscular, agile and athletic lizard. Monitors are also some of the most intelligent reptiles on the planet!

You can expect your Ackie monitor to live around fifteen to twenty years, so it’s definitely a commitment.

3 month old Ackie Monitor

The Ackie Monitor comes from arid regions of Australia. They are never wild caught as animals cannot be exported from Australia, so all of the Ackie monitors you will see in captivity over the last decade will have been captive bred. In captivity the Ackie monitor tames down well and doesn’t have the attitude of some of the larger monitors. Although we’d consider it an intermediate species, it’s the perfect beginner monitor!

The reason we consider it an intermediate species is a combination of the size enclosure, the additional heating requirements, maintaining humidity, and the additional time and patience needed to tame them in comparison to say, a Bearded Dragon. You can still keep Varanus acanthurus as a first time reptile, but you need to be prepared to create the correct habitat and understand their needs. If you’re buying for a child, an Ackie monitor isn’t always the best choice, as children tend to want to get hands on quite quickly and you’d have to ensure you were responsible for maintaining temperatures and humidity.

If you’re looking for an active daytime beginner lizard suitable for all ages consider our Bearded Dragon Care Guide as well.


The minimum we will sell for an adult Ackie monitor is a 48x24x24″ enclosure, but you could consider a 72x24x24″ setup, especially if planning on keeping a group. As an active species, there’s really nothing that’s too big, and they’ll also climb and use plenty of space, so if your floor plan at home doesn’t allow for more than floor space, consider adding height instead with plenty of climbing branches.

Consider buying one of our full setups, which can be assembled and wired for you free of charge if local. Please note that due to the increased night time temperatures (See Heating Section), the Bronze Bearded Dragon setup is not suitable – so it needs to be Silver or above for an Ackie Monitor.

Ask us for upgrading to a 5x2x2 or 6x2x2!

Don’t bother starting with a small enclosure for a baby, this is an extremely good hunter from day one, so as long as your temperatures are stable, you can save money by going for your adult enclosure.

Decor and Substrate

Dwarf Ridge Tailed Monitors like a bit of everything. They like to dig, so a deep substrate able to hold humidity is important. We recommend either a sand and soil mix, something like Arcadia’s EarthMix, or Orchid Bark.

Ackie Monitors like to climb, so having sturdy branches that utilize all the space in the enclosure are important.

Ackie Monitors like to bask, and particularly like very hot pieces of slate or raised basking platforms, so having a raised basking platform underneath the heat lamp is ideal. They also like to warm up in private sometimes, so having hiding areas directly underneath the basking is also important. Having caves or slatted wood / slate below your basking platform helps facilitate this.

They also like to hide, and feel secure. They particularly like to squeeze themselves into tight places and crevices. You can create an excellent hiding environment for Dwarf Monitors by layering slate, polysterene or resin to create tight spaces and plenty of hidey holes. Having other caves such as reptile hides and cork bark will also add a variety of secure spaces.

Heating and Basking

Ackie Monitors need hot daytime temperatures, so it’s important to get your enclosure first and test your temperatures out at home before taking your monitor home. Ambient temperatures should be around 38C (100F) on the hot side, and can be high 20sC (80F) on the cool side.

Having a hot basking spot is extremely important for Ackies, and we try to measure surface temperature rather than air temperature. This is a species that will sprawl out on a very hot surface, soaking up the heat from below and above. As covered in the decor section, we recommend a raised basking platform with a heat absorbent material such as a raised dark coloured slate tile. This will absorb and hold the heat from your basking bulb. Surface temperature, which can be measured with an infra-red surface thermometer as opposed to an air temperature thermometer, should be around 45-55C, but can go higher – as high as 70C if the ambient is still correct. This is why having the right basking material to absorb and hold the heat throughout the day is important for an Ackie Monitor.

Night temperatures can drop a little low than your coolside, down to around 23c / 75f. This is certainly warmer than most houses in the UK and this is why we require people to have night time heating when they buy a setup from us for Varanus acanthurus.

Daytime Basking – A high output basking spot needs to be on the hot side of the vivarium. The exact wattage will depend on your vivarium size and height to attain a hot spot of 38c. Since your vivarium is going to be a minimum of 48x24x24″, you’re most likely going to want a 150w bulb. If your house is cold or you’re going for a larger enclosure, you could also consider Halogen bulbs, which create a more intense directed heat, or an all in one MVB, which I’ll cover later in the UVB section.

Turn off your daytime basking at night time.

Night time Heating – We recommend a ceramic heater bulb on a thermostat to meet minimum night time temperatures.

We recommend using cage guards as best practice with all heat elements, to avoid any chance of them being touched and causing burning. Ackie Monitors are athletic and will climb and jump.

Controlling Heat – You should always control your heat sources with a thermostat. Your heat source plugs into the thermostat and a probe goes into the vivarium. The probe detects the temperature and then automatically adjusts the heating element to the correct heat output. This gives your animal the correct temperature at all times, whilst also saving electricity!

Measuring Heat – You should have a thermometer – either analogue, or digital – in the enclosure as it is possible for thermostats to be faulty and you want to double check that your temperatures are correct. Ideally having one on the hot end and the cold end, or having one with two probes provides you with the best information.

To measure surface temperature which is important for Ackie Monitor basking, you’ll want an infra-red thermometer as well.

UVB Lighting

UVB lighting is essential for Ackies although you’ll often see advice contradicting this in older care sheets. It was originally believed that no monitors need UVB, but the more we research and understand them, and the more veterinarians weigh in on the problems of MVB even in monitor lizards, the more we’ve come to realize how important it is for a full and healthy life. We actually recommend UVB in some form for all reptiles!

For your Ackie you want a basking zone that has between 4-6 UV Index which is quite high. To calculate this you need to measure approximately the distance from your UVB light to the main basking zone of the Ackie – this is not to the floor, but to where they most frequently bask. This should be a raised platform that we already discussed.

At a distance of 10-12″ you can use a T5 6%, T8 12% or equivalent bulbs. At 12-18″ (which is the distance most people will have in a 24″ high enclosure) you’ll want a T5 12% bulb – this is what we include in our Ackie Monitor Setup. If you’ve gone for a higher enclosure again, with a distance of 18 to 24″ between the bulb and your Monitor, you’ll want to go for a T5 14%, which is the highest output UVB bulb currently on the market.

The other option is to use an MVB – Mercury Vapour Bulb combined with a UVB tube. These bulbs are self ballasted and cannot be used with a thermostat, so you do need to be sure you test out your temperatures adequately before adding the animal. They are high output UVB and high output heat and are only suitable for large enclosures because of this. However, they do only cover a section of the tank, so in a larger tank such as 48″ and definitely in a 72″ tank, you’d still need a UVB tube covering the other end of the tank to make sure there’s full coverage across the entire length of the tank.

Your UVB lighting should be on for 10 – 12 hours a day, which you can set on a timer if you’d like. Always turn off your UVB lighting and your basking bulb at night time.


Keep fresh, clean water in the enclosure at all times. It does not need to be deep. Ackie monitors can swim if they have to, but are unlikely to choose to. They need a clean water source and will drink from a water bowl and a large bowl will also increase the humidity in the enclosure. They may choose to defecate in the water bowl and it’s important to change it every day. A Large or Extra Large Exo Terra Water Bowl is an ideal size for a 48x24x24″ enclosure.

There’s no need to bath your Ackie monitors and they’re likely to be very stressed if you do. If you do find that your monitor is having trouble shedding, you may want to double check your humidity and provide a damp moss box.


Although Ackies originate in Australia the habitat we’re creating is what you’d find along the edge of the forest, in rocky desert areas that have ample burrowing and basking opportunities. These areas often have a wet and a dry season as well. Overall ambient humidity can be around 60 – 65%, which is obtainable with a large water bowl and a quick daily misting to keep the substrate holding some moisture so that they can burrow. If you dig a hole in the substrate does it crumble and fill in, or hold shape? You want it to hold shape, but not feel wet.

In their burrows however, Ackie monitors would obtain up to 90% humidity. It’s important to give them enough substrate to burrow, and provide different hides and layers as we’ve already discussed. Having moss in one of the hiding areas, or just a box of moss in the enclosure that they can get in or out of, can be useful if they have shedding problems, but if ample burrowing opportunities are already provided, you may find that their shedding needs are already well taken care of.

Conversely, an enclosure with too much humidity overall can create health problems, so it’s something to be aware of and not go crazy with the misting or create a high overall humidity when humid burrows will suffice.

Social Needs and Housing Together

The vast majority of reptiles live a solo life, but Ackie Monitors are a species that are an absolute delight to watch socialise and interact. They do still have problems with male territorial behaviour, so keeping one male to a group is important. Housing hatchlings raised together is the best way to have a successful group, introducing adults can be much more difficult and monitoring needing, which leads onto sexing.

Sexing Ackie Monitors

Sexing Ackie Monitors as hatchlings is very difficult and impossible to guarantee. Experienced breeders may be able to give an accurate guess by 5-6 months, but it still wouldn’t be a guarantee at this stage. By around 9-10 months old it becomes much easier to sex them. Both sexes have spurs at the vent, but males are larger and more rigid. Males have a larger size overall, with a wider head and body.

Ackie monitors can reach sexual maturity quite young and are fast growing, with reports of large females as young as 6 months laying eggs. This is obviously a very easy determination of male or female – witnessing mating behaviour or seeing a monitor lay eggs. Others may not breed until 12 or even 18 months, depending on their growth and development.

Interestingly, there is a lot of theory with Ackie Monitors that if you buy a group of very young hatchlings, you almost never end up with more than one male. The group naturally appears to be one dominant male, with multiple females. There are questions about sex determination stemming from hormonal changes based on the social makeup of the group – but this hasn’t been proven scientifically, and is anecdotal. This theory, along with the fact that monitors raised together are often more socially compatible, encourages people to buy multiple hatchlings from the same clutch if you’re planning on cohabitating. You should always be prepared for a worst case scenario though, if you do end up with two dominant males you may need to separate or rehome one.


Varanus acanthurus is a keen predator and very food orientated. They have a fast metabolism, giving them their crazy bursts of energy. They can recognize a pair of tweezers or a box of food at quite some distance! In captivity we feed them a variety of livefood such as crickets, locusts, mealworms, lob worms, dubia roaches, earthworms, and higher fat content such as waxworms and occasional defrosted pinkie mice as a treat. In the wild, they’d also eat other lizards as well as raiding nests of eggs.

In captivity you can try them on boiled eggs as an excellent source of calcium and vitamins. Some will love them, some won’t be interested.

Livefood should be kept in cool, well ventilated containers and gut loaded with fresh dry vegetables, or a pre-made mixture such as our Livefood Care Pack which comes with both nutrients and hydration. Don’t use a water bowl with livefood, the humidity will cause them to die and they’re prone to drowning.


Food should be dusted with a multivitamin D3 supplement once a week and straight calcium on all other days.


Ackies are the most calm of all the monitor species. They can be flighty as juveniles and take patience over several months and regular interaction to tame down, but are highly intelligent and will easily recognize you as a source of food and not a threat. They can even tell the difference between different people. They are food orientated, so you can get them used to you by feeding on tweezers, putting your hand in the vivarium and gently interacting with them. As adults they’re usually docile and quite happy to be handled.

When handling, never pick up a a lizard by the tail or head. You should support them fully underneath the body.

Red or Yellow Ackie – what’s the difference?

Finally I want to touch on something that comes up a lot. You may see references to a Red Ackie, or Yellow Ackie. This actually doesn’t just refer to the colour of Varanus acanthurus, but refers to the subspecies as well. The Red Ackie is Varanus acanthurus acanthurus, whilst the yellow Ackie is Varanus acanthurus brachyurus and sometimes Varanus acanthurus insulanicus.

The simple truth in the UK is that although originally there were a lot of Ackies labelled red and yellow – I’m talking fifteen to twenty years ago now – captive breeders did not keep these subspecies identified and separated. People purchased and bred between the subspecies and you will be very hard pressed now to find a specific subspecies guaranteed. On top of that, Ackies show a wide range of colour anyway, and you may find in one single clutch – which most likely has both subspecies in it’s heritage – you see some red colouration and some yellow and orange colouration. This means that people often label Ackies as Red or Yellow purely based on the colour that they see from a single clutch, without properly understanding that these are not colour morphs but references to specific subspecies.

I really hope that this Dwarf Monitor (Varanus acanthurus) Care Guide has covered everything you want to know. If you have a specific question for us about our Ackie Monitors or setups then please drop us a message on Facebook or an email. Thank you!

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