This document contains information regarding of monitor lizards in captivity. I will try to persuade you to think about your ability to keep a monitor in captivity. This FAQ will also try to prevent you from getting in over your head, and helping you make a responsible decision on which species to keep if you decide to keep a monitor. Furthermore this FAQ serves as a means to provide the best possible information on captive monitor husbandry. I will try to contrast different husbandry techniques in order for YOU to determine which is best.
A lot of information available on monitor lizards is misleading. The pet trade is often responsible for spreading this inaccurate information about monitors. Pet stores will sell baby Nile monitors and tell the customer it will only grow to the size of the cage. They will tell customers it will be "dog tame" and a fun pet. They will sell a 30 gallon aquarium and tell the customer this is the biggest cage the monitor will need. They will tell you all the nile monitor will eat for the rest of its life is crickets. They will tell you monitors do not need much heat above room temperature. They will tell you anything they need to tell you in order to make a sell. All of this information is inaccurate and you will end up with a dead monitor. Monitor lizards, of any species, really are not for the beginner reptile keeper. The smaller species, such as varanus acanthurus or "ackies" , are great for first time monitors keepers. The larger species, such as varanus salvator or varanus niloticus, although cute little lizards as hatchlings, grow at tremendous rates and can easily be 4'+ by the end of their first year and can eventually grow upwards of 6'. There is no guarantee they will become tame no matter how much you work with them, and even a bite from an average sized monitor can cause severe damage not to mention an incredible amount of pain. Monitors will often use their tail as a whip for their primary defense. Their powerful limbs accompanied by their very sharp claws can also do some considerable damage not only to you, but to your belongings in the case of an escape. These animals are not cheap to keep as well. Their caging and food can easily reach over a $1000 a year so it is best to plan ahead.
Although I have done an incredible amount of research over the last two years and have been helped by others in writing this FAQ, this is by no means an end all document. I urge you to do your own research before purchasing a monitor. This is the most accurate information I can provide you, but that does not necessarily make it true. Monitor husbandry is relatively new and is continuing to evolve. Thus, what is said here today may not be true tomorrow. However, I will do my best to make this a living document and keep the information as up to date as possible.
Most species of monitors commonly kept in captivity can be kept in very similar ways. Their basic requirements are the same although some variation does exist. I will try to treat as many species as I can in their own sections, but this is based on the cooperation and information of others who keep them. However almost all the information gathered here can be applied to any species.
Monitor is the common name for lizards belonging in the family Varanidea. All monitors, as of now, belong to the genus varanus but they may soon be split into smaller groups including the Odatria group (Bennett 1998). Virtually all monitors are similar in appearance with the main variation being size. As of now there is still some confusion in the taxonomy of monitors lizards and considerable work needs to be done in the future.
Nobody knows for sure. As of now there are around 50 recognized species depending on who you talk to. However more are constantly being identified and there are many known yet undescribed species.
Monitors vary an incredible amount in size. The smallest is V. brevicauda which only reaches a size of 23cm (Bennett 1998). Determining the largest monitor is a bit trickier as it depends on your definition of largest. The komodo Dragon (V. komodoensis) is definitely the largest in bulk and near the longest as well. There are reports of komodo dragons being upwards of 9' although this may be unusual. This species is endangered and luckily is not available to the public. The longest monitor available in captivity is the crocodile monitor (V. salvadorii) and they too can reach upwards of 9' but the majority of that length is tail and they do not reach anywhere near the bulk of a komodo dragon. Two other large monitors, the water monitor (V. salvator) and nile monitor (V. niloticus) are also available and commonly kept in captivity.
Monitors grow at incredible speeds if they are provided the proper conditions. Heat and the amount of food given will affect a monitor's growth rate. A savannah monitor I have grew from 7" to 44" in a year and then grew from 44" to 48" in the next six months and has not grown since. Monitors grow very rapidly in their first year, under ideal conditions, and then slow down until they reach their maximum size.
Due to inaccurate records and the majority of animals being imported it is hard to say how long monitors live. They certainly can live to be over ten years of age and I have heard of water monitors being kept for over 20 years in captivity although I do not have proof of this. Regardless of the details, a monitor lizard is a long commitment and one should plan on it living for well over 10 years.