All monitors are listed as CITES II, except five. The following five are CITES I:
V. bengalensis
V. flavescens
V. griseus
V. komodoensis
V. nebulosus
Your animal could be captive born, and it probably was captive born. There are several people breeding argus monitors. However, I have heard of arguses still being imported even though I was under the impression that importation of argus was not currently allowed. Someone else can probably provide you with more details on the status of argus importation.
Arguses do come from dry, not desert, location. This does not mean you should keep it bone dry. In my opinion, it means they will tolerate dry conditions better than monitors unaccustomed to dry conditions. Your argus should still have water to drink. If you notice your argus trying to soak or sitting in the water for extended periods of time, then that is likely to be an indication that the enclosure is too dry. Mist down the substrate.
Unlike many keepers, I could not tell you off-hand what the humidity is in most of my enclosures for any of my monitors. I have the tools to find out if I feel I need to do so, but I do not regularly monitor temperatures or humidity. I gauge what I do by what they do or what the substrate looks/feels like.
What I have seen with my arguses is that they do not soak in their water containers at the same time my salvators flock to their water containers (this rarely happens as it is). Still, my baby waters are occasionally found swimming or floating or submerged in their water containers and an argus would not even be thinking of soaking. Also, whereas my salvators rarely seem to mind a torrential downpour (via the hose), my argus usually have a lower tolerance for the same level of water.
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^x^ Bloodbat ^x^
Monitors, monitors everywhere
and all the food they ate.
Monitors, monitors everywhere,
their parents loved to mate.