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Bosc Monitor

(Varanus exanthematicus) 



The Bosc or Savannah Monitor (Varanus exanthematicus) is a medium sized lizard that are found in the hot arid conditions of the Savannah in Africa. They are a terrestrial species that are mainly found at ground level although they will go into low level bushes & trees, and also burrows.


Size & Lifespan:

If kept correctly, they should have an average lifespan of 10-15 years however, 20+ years has been recorded.
An average sized adult will reach between 2.5ft – 3.5ft.



As babies a 4ft enclosure is a perfect size to raise them in, whereas an adult is going to need a minimum of a 6ft long enclosure by 2-3ft wide.



A soil & sand mix is perfect for this species. Many substrates are now available pre-mixed such as the Pro-Rep Tortoise Life or Pro-Rep Desert Life, either of which are suitable for a bosc monitor. These substrates are also perfect for misting lightly, this will help with them for digging around & also especially to help aid your bosc in the shedding process. As adults they will benefit from a deep substrate to allow digging.



Heating and Temperature are very important to the health of your Bosc Monitor. Boscs need heat to thermo-regulate, as they do not produce their own body heat internally. They need an external heat source to help them digest their food as well as regulate other bodily functions.
A Daylight Basking Spot or a Ceramic Heat Emitter controlled by a Thermostat is perfect to provide a Basking area for your Bosc. The basking area temperature should be around 36-38C (96-100F). Although some keepers prefer slightly higher temperatures of 40-43C (105-110F).
At night time, the temperature should be allowed to drop to around 20C (your average room temperature should be just fine, although you may have to keep an eye on this during the winter months). It should not drop below 15C.


Lighting & UV:

UVA & UVB Lighting is essential for a Bosc Monitor. UVA is responsible for normal behaviours such as feeding, how active they are, mating, etc. UVB, is a non-visible wavelength which allows the synthesis of vitamin D3 to ensure that your Monitor is able to absorb calcium for its bones. Without it, they can develop Metabolic Bone Disease (MBD).  Metabolic bone diseases are disorders of bone strength, usually caused by abnormalities of minerals (such as calcium or phosphorus), vitamin D, bone mass or bone structure.
A 10-12%/Ferguson Zone 3 UV Tube (T8 or T5) should be used & it should cover as much of the length of the enclosure as possible to give a full spectrum. Please pay attention to the manufacturer’s directions for replacement of these UVB bulbs as they are all different… some advise replacement every 6 months, others 9 or 12.
The UV should be left on for 12 hours a day & then turned off at night.


There are many different brands of supplements on the market, all containing different levels of vitamins & minerals. Some contain D3, others not. Over the years, there have been advancements in UVB lighting with the option of T5 now readily available... before T5 lighting, keepers relied more on supplements containing D3 to ensure their reptiles absorbed calcium & phosphorous for their bones. However with the correct UV lighting, a healthy Bosc monitor will produce its own D3, so you may not actually need any synthetic D3 by means of supplementation.


So do you use supplements with D3 or without is the question??

Well if you have a good understanding of the UVB & husbandry requirements needed for the species, and have a radiometer to measure the UVB levels a couple times a week to check they are correct, then there is a good chance you can use supplements without D3, which is a more natural way.
However, if you don't have a radiometer to measure the UVB output or you're just not completely 
confident that you are providing the correct levels, then a safer option is to use a pre-balanced supplement with some D3. The main downside to synthetic D3 is that overdosing could cause a deficiency in vitamin A but as long as you have a good pre-balance multivitamin it’s unlikely to be an issue.

If you have purchased a setup in store, you were likely to have received a simple calcium powder without D3 and a pre-balanced high calcium multi-vitamin with some D3 called Nutrobal. For most of the animals we alternate these daily.

If you have different supplements to these, please do not hesitate to speak to us with regards to their use.


A Bosc Monitor should have a diet that consists 90+% of insects. Insects such as Crickets, Locusts, Roaches & Worms can be given to your bosc (worms should be limited, especially to babies as they can bung them up). They can also be given feeder snails & some shellfish such as oysters & crabs.
There is much debate over feeding rodents to Bosc Monitors...we would personally advise no more than 1-2 times a month feeding rodents or a boiled egg. If overfed on rodents, this can led to kidney & liver damage... something that we have sadly faced ourselves with our 
own pet Bosc Monitor dying at a very young age due to his previous owner feeding mainly rodents & offal. Even though we had changed his diet to the correct one, the damage had already been done & was irreversible.


Temperament & Exercise:

Boscs can tame down very well if you put the effort in with them. They can be challenging & do have a number of defences which include hiding, running away, acting shy or docile (limp), closing their eyes & playing dead, tail whipping, hissing & biting. It is important to gain your boscs trust & do things slowly… we can give you some tips to try with this.
Boscs can also be lazy & will happily just sit in once place for ages if left to do so, this will lead to a unhealthy & more than likely fat lizard… as your bosc gets older & starts to trust you more & become less skittish, you could look at getting him or her out of there enclosure for a walk around… you may need to start off with a lead & harness initially but it is very common to be able to get them tame enough to just mooch around a room.
Another thing many keepers do is they give their Bosc a bath once a week… this is great for exercise, aids in helping with the shedding process & also good for bowel movements.


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