
Asian water monitor
Varanus salvator
Photo: Varanus salvator - 01 · Carlos Delgado · CC BY-SA 4.0 · Changes and credits
These guides provide general husbandry information and do not replace veterinary assessment. If your animal shows symptoms or its condition worsens, contact a veterinarian experienced with exotic animals.
- Warm zone
- About 52–60 °C · surface
- Cool zone
- About 27–29 °C · air
These notices cover the cited provisions, not every possible national or local rule. Check additional requirements with the competent authority.
Description
Varanus salvator is a large monitor from southern and southeastern Asia, widespread around rivers, swamps and mangroves. Its long laterally compressed tail aids swimming, while its claws allow digging and climbing. It is diurnal and opportunistic; colour and size vary between populations and subspecies.
Behaviour
Explores ground, supports and pool. Brief predictable interactions allow observation of individual responses.
Housing together
House animals individually with freely accessible hides. Prepare separate accommodation before any introductions.
Enclosure and climate
Provide sturdy platforms and branches, digging substrate and a pool with accessible exits. Guard filter intakes because strong suction can trap the animal.
Basking surface about 52–60 °C; air about 27–29 °C. Retain a retreat area and measure air and surface separately.
Setup
Before completing furnishings, fill and empty the pool to check that water cannot reach bedding or electrical equipment.
Guard filter intakes and make guards removable for cleaning.
Routes and pool
Size the pool for the adult body, with room to enter, turn and leave. Secure access from bottom to rim and connect branches to platforms, testing supports under load when wet too. Leave a dry route to the cool retreat without required jumps across water and keep the drain and filter accessible.
Testing and access
Connect specified heat sources to compatible thermostats and guard against contact. Secure probes according to device instructions; measure air at resting sites and heated surfaces separately with independent instruments. In housing with water, also check water temperature and quality: one zone’s thermostat does not control the others.
With the complete enclosure running, record day and night readings and compare them with the sheet. Test doors, cable openings and cleaning access, keeping vents clear. Change one variable at a time and recheck after each adjustment.
Lighting and UVB
Ferguson zone not assigned with sufficient precision to this taxon.
At the exposed position aim for approximately UVI 4–6, measured at the back or head. The animal must choose its exposure and reach UVI 0 retreats. This local target differs from the Ferguson ecological band and should not be maintained everywhere throughout the day.
UVB is essential in indoor housing. Outdoors, direct sunlight can provide it if shade is always accessible. Select the lamp to achieve the appropriate UVI at the positions the animal uses.
UVA is recommended as part of daytime lighting, including when UVB has not been shown to be indispensable. Check the UVB source’s spectrum, as it may already emit UVA: a second lamp is not automatically necessary.
Linear UVB tube with reflector. Indicative UVB percentage stated on the lamp: 10–12%; final selection depends on UVI achieved at the actual distance.
For maintenance, a cycle of approximately 12 hours of light and 12 hours of darkness can serve as an initial reference. Use a timer to switch lights off at night, and keep retreats available so the animal can withdraw from light during the day. Adapt day length to species and origin, following the specific guidance for seasonal care and breeding.
Light in the animal’s daily life
Measure at back height on the dry platform and climbable structures. Provide ample retreat areas as well as the pool; water does not replace a shaded hide.
An example layout in the enclosure
To make the layout concrete, take housing measuring 244 × 183 × 244 cm, using the first dimensional configuration in the sheet. This is a mounting example: retain the conditions and any alternatives attached to the stated minimum.
In a wooden enclosure with internal lighting, imagine the tube 239 cm above the floor and the back or head at 199 cm. The geometric distance is therefore 40 cm. The branch or platform lies below animal height, according to body size. Place lighting over one side, with a route to fully screened retreats.
In a glass enclosure with a mesh roof, retain the same animal height and imagine the tube 5 cm above the mesh: distance becomes 50 cm. Mesh attenuates UV variably; ordinary glass roofs block UVB. Increasing the percentage alone is insufficient: measure beneath the mesh and adjust height, output or layout as needed.
These distances describe the example, not a safe clearance for every lamp. Select the source and adjust mounting until approximately UVI 4–6 is measured at animal height in the exposed position. Also respect the minimum clearance specified for the model used. Recheck with furnishings, guards and mesh installed, including the highest reachable points and animal growth.
Choosing and checking lighting
First define the patch that should illuminate the whole body and the route to a screened retreat. For a broad patch, select a linear tube with reflector; consider a compact only if its useful patch covers the body and leaves an accessible gradient. Check model, output, reflector and mounting distance, then compare measured UVI with the species target. Label UVB percentage alone cannot determine distance and intensity.
The decisive check uses a UVI metre facing the source at animal height. Check the centre and edges of the exposed patch, the highest supports and retreats, which must allow withdrawal from UV. Repeat after moving equipment, changing lamps and plant growth. Without a metre, use the manufacturer’s instructions and measurements for the exact configuration, including safety clearances.
When UVB or UVA are absent
If the UVB source fails, restore the installation and recheck the exposed area. Oral D3 may be considered as temporary support but is not a complete or universally safe replacement. Consider calcium, D3, diet and animal condition together: avoid improvised extra doses.
UVA contributes to environmental perception and behaviour and cannot be replaced by vitamins or calcium. A reptile UVB source normally also emits UVA: check its declared spectrum. If the existing lighting lacks it, complete the installation with a suitable source; an ordinary white LED does not guarantee UVA and a UVA-only lamp does not provide UVB.
Humidity and ventilation
Maintain humidity at 60–70%, with air exchange and clean water. Measure near hides without letting the hygrometer touch wet bedding, and also inspect substrate beneath retreats. If readings stay outside the specified values, check blocked vents and standing water before adjusting water input; recheck after the change.
Feeding
Varanus salvator: carnivore; vary insects, invertebrates and appropriately sized whole prey. Minced meat alone lacks skeletal calcium. Avoid large daily meals in adults.
Recommended foods
The tiers describe dietary use: rotate foods within each tier rather than treating them as an absolute nutritional score.
| Food | Dietary role | Benefits and limits | Preparation |
|---|---|---|---|
| Whole captive-bred thawed rodents | Main choices | Skeleton, organs and muscle together supply nutrients absent from meat alone; select prey size according to swallowing ability and the portion specified for the species. | Thaw completely in a refrigerator in a container separate from human food, then warm in a sealed bag in warm water. Do not microwave or refreeze. |
| Crickets and locusts | Main choices | Supply protein and encourage hunting; calcium is low relative to phosphorus, so preparation and supplementation are needed. | Use captive-bred insects and gut-load them as described below. Select suitably sized feeders, place the meal’s batch in a clean container and apply a thin calcium coating immediately before offering them. |
| Feeder roaches | Main choices | These feeders provide a useful second protein source for rotation, but do not constitute a complete diet or replace calcium supplementation. | Offer well-fed soft nymphs sized to the mouth; avoid excessively hard adults. |
| Earthworms from controlled cultures | For rotation | Soft prey with a generally more favourable mineral balance than unsupplemented crickets; particularly useful for amphibians. They are not a reason to eliminate all variety. | Rinse and cut only if required for mouth size. Avoid dyed fishing bait, cultures on contaminated manure and collection from treated soil. |
| Suitable whole fish and molluscs from controlled suppliers | For rotation | Provide variety; fillets are not equivalent to whole prey. Composition varies between species and not all fish suit routine use. | Identify the species: avoid goldfish, unspecified mixtures, excess oily fish and salt. Thaw completely; do not collect from unknown waters. |
| Boneless meat and organs alone | Avoid / not a staple | Do not replace whole prey: muscle meat is calcium-poor and a liver-only diet can supply excessive vitamin A. | Do not use steak, boneless chicken or processed meats as the regular diet. |
| Live rodents | Avoid / not a staple | Live prey can bite and seriously injure the reptile. Its movement does not improve the meal’s nutritional balance. | For animals refusing thawed prey, assess temperature, health and presentation technique before changing prey. |
Comparable nutritional values
Protein, fat, calcium and phosphorus are percentages of dry matter, excluding water; dry matter itself is a percentage of fresh weight. These are reference analytical values compiled in a clinical table, not guaranteed contents of your batch or a universal ranking. Age, rearing, feeding and supplementation change composition. Do not compare them directly with fresh-food percentages or already diluted prepared diets. Comparable numbers are not provided for other foods.
| Insect | Dry matter | Crude protein | Crude fat | Calcium / phosphorus | Ca:P |
|---|---|---|---|---|---|
| Adult house cricketAcheta domestica | 32% of fresh weight | 62.6% DM | 20.4% DM | 0.3 / 1% DM | 0.3:1 |
| Migratory locustLocusta migratoria | 31% of fresh weight | 67.5% DM | 14% DM | 0.1 / 0.7% DM | 0.14:1 |
DM = dry matter. Ca:P describes calcium relative to phosphorus before supplementation: a protein-rich feeder may still be calcium-poor. Offered portions remain those for this species and life stage.
Meals by age and size
| Stage and size | Frequency | Amount per meal |
|---|---|---|
| Young: from first feeding until growth is well established | Daily | Small insects as the base: offer small batches for about 5 minutes, recording intake and weight. Vertebrate prey only when swallowable, replacing some insects. |
| Juveniles and subadults: still growing noticeably | Every other day | One measured portion of whole prey or invertebrates: each bite must be swallowed easily. Reduce the count as prey size increases; do not add rodents to an already complete meal. |
| Adults: near final size, growth has slowed | 2–3 meals weekly | Start with one small whole prey item, swallowed without strain, or a measured portion of invertebrates. Weigh the meal and compare animal weights before feeding: adjust gradually rather than feeding to apparent satiety. |
Adjusting portions
To assess the portion, compare the amount and type of food eaten with growth and body condition. Weekly weighing of juveniles and monthly weighing of adults helps follow the trend. Adjust the ration gradually when growth or reserves require it; reduce it if body condition indicates excess weight or leftovers remain. Investigate unexpected weight loss or abnormal swelling rather than addressing it only with more or less food.
Preparing and offering meals
Prepare insects during the 24–48 hours before feeding: keep them in their culture container with a complete feeder diet and safe hydration. Check access to food and water and remove spoiled leftovers. Then select feeders of the specified size and prepare only the batch to be offered. This step, called gut-loading, improves prey quality; bran or potato alone do not correct deficiencies.
At feeding time the prey should be easy to swallow. As an initial guide, choose insects no wider than the space between the eyes, then adapt size to the mouth and the animal’s response. Offering them individually or in an escape-resistant dish lets you see actual intake and remove leftovers.
Thaw completely in a refrigerator in a container separate from human food, then warm in a sealed bag in warm water. Do not microwave or refreeze.
Trial amounts are a starting point for a healthy, active animal at correct temperatures: record intake and weight trend, then adjust the ration. Do not feed again merely because it continues striking at prey.
Calcium and vitamins
Immediately before feeding, lightly coat low-calcium insects with phosphorus-free calcium: they should remain visible, without clumps. Common insects often have an unfavourable calcium:phosphorus balance; rotating them alone does not correct it.
Supplement the insect component; do not automatically add the same dose to every whole prey item. Meat recipes require calcium and vitamin formulation rather than casually dusted meat.
Choose one supplementation programme: plain calcium for ordinary meals and a species-appropriate multivitamin at its labelled feeding intervals. Record the product and its existing D3 and vitamin A; do not add a second dose to meals using a combined product. With measured UVB, agree the oral D3 provision; product concentrations are not interchangeable.
Daily care
First days
Before arrival, run the complete enclosure and check conditions at resting positions. Prepare water, food and a transfer container. Record the portion offered, leftovers and weight; observe from outside and open hides only when necessary for cleaning or transfers.
Cleaning
Each day check water and collect waste, including beneath retreats, with dedicated tools. Clean dishes and replace their water; for pools follow the species’ water-change plan. Wash your hands afterwards. Keep animals and equipment away from kitchens and food areas, use tools dedicated to each enclosure and wash your hands with soap and running water after handling animals, food, tank water or furnishings. Quarantine new arrivals separately and agree the duration and checks with a veterinarian before introducing them to established animals.
Handling
Allow voluntary approaches and leave a retreat route available. For transfers, prepare a container and assistance appropriate to the animal’s size. Do not lift it by the tail or force it out of a hide.
Checks
Check weight, appetite, movement and skin; consult a veterinarian experienced with the species if changes persist. Wounds or laboured breathing require prompt contact without waiting for them to persist.
Breeding
Sex, maturity and readiness
Verify species, subspecies and origin within the water-monitor complex. Confirm sex and growth, good muscular condition and independent housing suitable for adults. The trade name alone does not determine a breeding calendar.
Start a record for each breeding animal with identity, origin, documented age and previous weights. Compare the weight trend with growth and body condition; delay introductions for animals still growing rapidly, losing weight or recently acquired. Use stated ages as guidance alongside these checks. If sex cannot be identified reliably, obtain assessment by qualified personnel before pairing.
Preparation and seasonal cycle
Maintain a clean pool, broad land area and stable gradient. Introduce gradual locality-specific seasonal changes without cooling the entire system. Prepare nesting and a separate nursery with systems able to support many large growing animals.
Before encounters, prepare and test offspring enclosures and have first foods available. Check records for regular adult feeding and good body condition, then verify access from exposed areas to retreats. If the species protocol includes seasonal changes, adjust settings gradually and record the response. Record night-time air, surface and egg temperatures separately, noting where each is measured. Keep water available throughout preparation.
Courtship and mating
Observe encounters in space with broad access, supports and retreat routes. The female must leave water without being blocked. Record mounting and copulation and separate if pursuit or injury occurs; keep an adult-management barrier ready.
Before laying and the nest
Prepare an opaque terrestrial nest with moist diggable medium, separate from the pool: laying in water can compromise eggs. Check site searching and digging and provide privacy. Recover the clutch when the female moves away, recording eggs, origin and orientation.
Maintain a suitable laying site even without a male: females can produce unfertilised eggs. Persistent straining without laying, weakness or tissue protruding from the vent require prompt veterinary assessment. Do not wait for a predicted laying date if these signs appear. Do not squeeze the abdomen, pull eggs or give drugs to induce laying without veterinary direction.
Egg incubation
Development may require many months. The form historically described as V. salvator komaini has documented hatching after about 240 days at 25–26 °C: this combination must not automatically be transferred to other origins. Choose a regime established for the identified lineage and measure at egg level without deriving temperature from a timetable.
Test the system before laying with an independent probe at egg height. Use clean, labelled containers, closed but allowing air exchange, with room for eggs and hatchlings. Keep eggs in their original orientation and do not detach eggs glued to their support. The substrate should retain moisture without free water on the shell; check condensation and water loss, adding water at the edge of the substrate rather than onto eggs. Record temperature and events daily without needless opening. The stated times are approximate: do not increase heat to meet a date.
First meals and juvenile care
Provide small cleanable pools with low exits, supports, shelters and ample land. Follow the juvenile diet with appropriately sized prey and individual monitoring; prevent food decomposing in water. Separate different sizes and frequently increase housing dimensions and filtration.
During the first weeks, monitor each youngster: a feeding group does not guarantee that every individual eats. Record intake, droppings and weight at regular intervals to follow growth and adapt housing and food size. Provide separate accommodation if competition prevents an individual from feeding or size differences become marked. Document repeated independent meals before transfer to another keeper.
Female recovery
After reproduction provide water and the usual balanced diet, initially in manageable portions; monitor weight, activity and return of appetite. Keep supplements and lighting consistent with the feeding guide. Avoid further introductions until the previous condition has recovered; later clutches may occur without another mating. Persistent straining, weakness or protruding tissue require veterinary attention, without squeezing the abdomen.
Equipment and example diary
Place the nest where it can be checked without dismantling the enclosure. Label containers with female identity and laying date and prepare the specified medium; for attached eggs, instead provide guards in place without detaching them. If using an incubator, install a thermostat and independent probe and test it before laying. Run offspring enclosures too and prepare scales and first food, reserving capacity for later clutches.
A consistent diary using actual dates helps follow reproduction in Varanus salvator. Start with adult identity, weight and condition, then record observed encounters, laying or birth and development conditions. After emergence record the first meal actually accepted and each youngster’s growth while continuing to follow female recovery. Over time these records help identify your lineage’s pattern without turning approximate durations into deadlines.