Geckos

The Thick-Tailed Gecko (Underwoodisaurus milii) is widespread across southern Australia, with a range extending from southwestern Western Australia through South Australia, Victoria and into New South Wales and southeastern Queensland. It inhabits a wide variety of arid and semi-arid environments — rocky outcrops, mallee scrubland, open woodland and grassland — where it shelters beneath rocks, in rock crevices and under loose bark during the day, emerging at night to hunt.

The Smooth Knob-tailed Gecko (Nephrurus levis) is similarly widespread across the arid interior of Australia, ranging through Western Australia, South Australia, the Northern Territory and western Queensland. It is a true desert specialist, found in sandy spinifex grasslands, red sand dunes and arid shrublands. Like all Nephrurus species, it is characterised by its distinctive small, spherical tail knob — a feature unique to this genus and thought to play a role in distraction or mimicry of the head when threatened.

Both species are strictly nocturnal and terrestrial, spending the heat of the day sheltered underground or beneath rocks. They are remarkably well adapted to arid conditions and are among the most rewarding Australian gecko species available in captivity. Thick-Tailed Gecko: 14–16 cm total length. Smooth Knob-tailed Gecko: 12–18 cm total length. Both are robust, stocky-bodied geckos.

Both the Thick-Tailed Gecko and Smooth Knob-tailed Gecko are terrestrial and require floor space rather than height. A minimum enclosure size for a single adult is 60 cm L × 40 cm W × 30 cm H; a 90 × 45 × 30 cm enclosure is preferred and allows a more effective thermal gradient, particularly for the Smooth Knob-tailed Gecko, which benefits from additional space to thermoregulate across a longer temperature range.

A thermal gradient is essential: the warm end should be maintained at 30–35 °C using a heat mat or heat cord positioned on the side wall or underneath one end of the enclosure, regulated by a quality thermostat. The cool end should sit at 22–26 °C. Night-time temperatures may drop to 18–22 °C, which is appropriate for both species. Heat rocks must never be used — they are a common cause of thermal burns and are not suitable for any reptile.

Substrate is a critical consideration. A deep layer (8–12 cm) of clean, reptile-safe desert sand, or a sand and soil mix, allows both species to express natural digging behaviour — particularly important for Smooth Knob-tailed Geckos, which are accomplished burrowers in the wild. Avoid calcium sand, which can cause digestive impaction if ingested.

Provide multiple hides — at least one on the warm end and one on the cool end, as well as a humid hide containing slightly moistened sphagnum moss to support shedding. Flat slate rocks, cork bark pieces and smooth stones provide additional shelter and basking surfaces. A shallow, escape-proof water dish completes the setup. UVB lighting, while not historically considered essential for nocturnal species, is increasingly recommended at a low level (T5 6% on a 10–12 hour cycle) and is thought to support overall health and natural circadian rhythms.

Both species are insectivores and require a diet of live invertebrate prey to stimulate natural hunting behaviour. Crickets and wood cockroaches (woodies) form the dietary staple for both species. Mealworms, black soldier fly larvae and silkworms can be offered for variety; waxworms are high in fat and should be reserved as occasional treats only. Smooth Knob-tailed Geckos, being larger-bodied, may occasionally accept a small pinky mouse — this can be offered once every two to four weeks as a supplementary food item but is not a dietary requirement.

All feeder insects must be gut-loaded for at least 24–48 hours before offering to maximise their nutritional value. Dust insects with a calcium supplement at every feeding, and with a combined multivitamin supplement every two to three feedings. Feed juveniles every one to two days; adults every two to three days. Offer food in the evening as both species are nocturnal hunters. Remove uneaten insects from the enclosure before lights on the following morning to reduce stress. Fresh, dechlorinated water must be available in a shallow dish at all times.

Both species can be handled briefly for health checks, enclosure maintenance or occasional gentle interaction, but neither is well suited to regular or prolonged handling. Thick-Tailed Geckos are typically the more tolerant of the two and may accept brief, gentle handling. Smooth Knob-tailed Geckos tend to be more skittish and are better appreciated as display animals. Neither species should be handled frequently.

Allow newly acquired animals at least two weeks to settle before any handling is attempted. When handling is necessary, do so close to the ground to minimise the risk of injury from a fall, as both species can move with surprising speed when alarmed.

Support the body fully — never grip or restrain tightly. Both species are capable of tail autotomy (deliberate tail dropping as a defence mechanism) if they feel threatened; tails regenerate but the regenerated tail differs from the original. Geckos should never be housed with other species. Two females may cohabitate in a sufficiently large enclosure, but males must always be housed separately as they are territorial.

Nocturnal geckos benefit most from a naturalistic, complex environment that allows expression of their natural behaviours. A deep, diggable substrate is the most important form of enrichment for both species — the opportunity to burrow, excavate and choose their own shelter position is fundamental to their wellbeing, particularly for Smooth Knob-tailed Geckos. Multiple hides of different sizes and positions give both animals genuine choice about where they rest and shelter.

Provide a variety of smooth rocks, cork bark pieces and low artificial plants to create visual separation and varied terrain. Rotating and rearranging furnishings during routine cleans provides novelty and encourages exploration. Varying the species and size of feeder insects offered each feeding — crickets one session, woodies the next, silkworms occasionally — stimulates natural hunting behaviour and prevents dietary monotony. Dimming or red-spectrum nocturnal lighting can allow observation of natural hunting behaviour in the evening without disturbing the geckos.

Incomplete shedding (dysecdysis) is the most common issue encountered, particularly retained shed around the toes and eyes. It is almost always caused by insufficient humidity during shed — a humid hide containing damp sphagnum moss resolves most cases. Never forcibly remove retained shed; allow the gecko to soak briefly in shallow, lukewarm water and allow the shed to loosen naturally. Retained shed around toes, if left unaddressed, can constrict and cause permanent injury or digit loss.

Thermal burns occur when heat mats or cords are not thermostat-regulated, or when heat rocks are used — ensure all heat sources are connected to a quality thermostat and avoid heat rocks entirely. Nutritional deficiencies including metabolic bone disease can result from inadequate calcium supplementation or poorly gut-loaded feeder insects — correct supplementation and gut-loading are essential preventative measures.

Mites and other ectoparasites can affect captive geckos — inspect animals and enclosure regularly, particularly in the substrate and under hides. Internal parasites are common in newly acquired animals; a faecal check at the first veterinary visit is recommended. Any signs of weight loss, lethargy, abnormal posture or changes in feeding behaviour warrant prompt assessment by a reptile-experienced veterinarian.