I congratulate you for thinking seriously about this issue – large monitor lizards can inflict serious injury by scratching or biting if handled inappropriately. The keeping of monitors is relatively straightforward compared to some other lizards but is not recommended for beginners. While many larger species commonly sold as pets tend to be quite docile and tame if handled regularly from youth, most animals can be difficult to handle and aggressive if imported as an adult.

I believe the smallest monitor lizard available in the pet trade is the Spotted Tree Monitor (Varanus timorensis). This species grows to a maximum length of about 28 inches, although is known to be nervous and difficult to handle. This species is not yet as widely available as other species sold as pets. The most common monitors sold in the pet trade are the African savannah monitor (Varanus exanthematicus) and the African Nile monitor (Varanus niloticus). Both of these species can easily achieve a length of 4 feet and can grow up to 5 and 7 feet respectively. One of the largest minors sold as pets is the Asian water monitor (Varanus salvator), which can grow up to a whopping 9 feet but is thought of as one of the most docile species. A few other monitor species are regularly available in small numbers in the pet trade such as Dumeril’s monitors (Varanus dumerilii), black rough-necked monitors (Varanus rudicollis) and mangrove monitors (Varanus indicus). These are moderately large and relatively easy to manage.