Furry Diary

Scaly friends count too.

Ackie Monitor

Varanus acanthurus

Also called Spiny-tailed Monitor, Ridge-tailed Monitor, Ackie Dwarf Monitor, Australian Spiny-tailed Monitor, Red Ackie

SpeciesShort profile

From Northern and central Australia: northern Western Australia, the Northern Territory and western Queensland, plus offshore islands such as Groote Eylandt. Lives among arid rocky ranges and outcrops with spinifex grass.12

At a glance the quick version

Length44 to 76 cm21
Lifespanfrom 15 years2
Sizemedium
One of the smallest and most manageable monitors to keep
Clever, alert and fun to watch
Busy daytime lizard that loves to dig
21

Looks how to spot one

Small scales with a spiny, ringed tail

A slim, compact monitor with a long whip-like tail covered in rings of spiky, keeled scales. The back is rich dark brown, reddish or black-brown, sprinkled with yellow, cream or red eye-spots, and pale stripes run from the face down the neck. The belly is light.21

Coloursdark brownredblack-brownyellow spotscream spotspale belly21

Personality what they are like

Bright, inquisitive and energetic, as monitors tend to be. Ackies are active by day and spend a lot of time exploring, digging and basking. They are considered an intermediate-level pet that rewards a keeper who enjoys setting up a rich, engaging home.21

Daily activity how busy a day looks

Very active during the day. Needs deep substrate for burrowing, rocks and climbing materials, and a large enough enclosure to patrol and hunt.31

Grooming and care the hands-on bits

Keep fresh water in a shallow bowl at all times and clean the bowl weekly. Check temperatures with digital thermometers and an infrared temperature gun. Lightly dust insects with calcium and use a reptile multivitamin now and then.45

Home where they are happiest

Minimum for one adult about 150 x 75 x 120 cm (5 x 2.5 x 4 ft) with a front opening, good ventilation and a substrate layer up to about 60 cm deep for burrowing. Very hot basking surface of 70-78 °C, warm-side air 29-38 °C, cool side 24-28 °C, with heat lamps off at night. UVB lighting is part of the setup.35

Food basics what goes in the bowl

Mainly insects: crickets, roaches, grasshoppers, worms, silkworms, black soldier fly larvae and similar, with occasional quail eggs or other small whole prey. Young ackies eat daily; adults every other day. Wild ackies get much of their water from their food.41

Company who they like around

Naturally solitary and happy living alone. Keeping more than one is a job for experienced keepers only; males should not share, and a single male-female pair in a much larger enclosure is the most workable combination.31

The story where it all began

George Albert Boulenger described the species in 1885 from Australian specimens. Three subspecies are recognised, and genetic work in 2006 suggested the island form may deserve species status. In the pet trade, captive-bred animals are sold as red ackies and yellow ackies, which roughly match two of the subspecies.1

Fun facts for the dinner table

  1. 1

    The spiky rings on its tail help it wedge itself firmly into rock crevices.1

  2. 2

    Around 70% of the water a wild ackie needs comes from the food it eats.1

  3. 3

    Its tail can be more than twice as long as its head and body combined.1

  4. 4

    Ackies like a sizzling basking spot, with surface temperatures of around 70-78 °C recommended.5

  5. 5

    Hatchlings are only about 15 cm long when they emerge from the egg.1

Recognised by the official bits

IUCN Red List
Least Concern.1
Taxonomy
Described by Boulenger in 1885; three subspecies recognised: V. a. acanthurus, V. a. brachyurus and V. a. insulanicus.1

The care rhythm Furry Diary remembers it for you

A typical home-care rhythm for a Ackie Monitor. It is our own starting plan, not a vet's advice, and you can change every line in the app.

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Where this comes from

Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at [email protected] and we will fix it.

  1. Spiny-tailed monitor - Wikipedia en.wikipedia.orgused for names, range, size, appearance, diet, behaviour, taxonomy, IUCN status, fun facts
  2. Ackie Monitor Care Guide - ReptiFiles reptifiles.comused for size, lifespan, origin, appearance, temperament
  3. Ackie Monitor Enclosure Size - ReptiFiles reptifiles.comused for enclosure, substrate depth, cohabitation
  4. What Do Ackie Monitors Eat - ReptiFiles reptifiles.comused for diet, feeding frequency, supplements, water
  5. Ackie Monitor Temperatures - ReptiFiles reptifiles.comused for temperatures

Checked 2026-09-30. Text is written in our own words from these sources.