Hatchling Care

If you have been fortunate enough to successfully hatch a varanid of any species, you will quickly realize that from the moment they enter this world, they display a remarkable array of behaviours, attitudes, and colours. These characteristics stay with them throughout their life, and are what convert the general reptile hobbyist into the extreme varanid enthusiast.

A healthy hatchling monitor lizard should be virtual indestructible. When proper housing, dietary, and social requirements are met, all of the historically common problems keepers experience with hatchling varanids can be avoided. To ensure the health and future reproductive viability of our hatchling monitors, several guidelines and practices are followed and implemented here at Canadian Coldblood.

Captive Environment
Hatchling monitor lizards will thrive in a relatively simple enclosure. A standard fifteen gallon glass aquarium seems to work well (Volume = 60cm X 30cm X 30cm). The lid of each enclosure should retain heat well, but also allow for adequate air flow (1/4” peg board is an ideal material for this application). Each lid is equipped with a light fixture which holds a standard 30watt spot light over the basking area. The basking area is located about 15cm (at a distance of approximately _ the ceilings total length) from one side of the enclosure. Cypress mulch is the preferred substrate for hatchlings. It is relatively hygienic, dust free, pleasant smelling, and provides them with many tiny crevices in which they can explore, hide, and use to search for prey. Flagstone is stacked securely below the basking spot. The distance between the spot light and the basking surface is approximately 15cm. This ensures that basking area will reach the desired temperature of approximately 50°C (120°F - 130°F). Basking and ambient temperatures within the enclosure may fluctuate due to external conditions. Flagstone is used for the basking area instead of a wooden stack for several reasons. Stone is easy to clean and holds heat well. This is beneficial for hatchlings because it gives them a warm place to hide at night when the lights are turned off. Cage furniture can consist of flat pieces of wood or bark placed directly on the substrate. This provides the hatchlings with a tight, secure place to hide, and search for prey. Many of the cage furnishings commonly purchased are more aesthetically pleasing to the keeper rather than useful for the monitor. But, these furnishings can be provided without any detriment to the enclosure inhabitants.

Water/Food and Nutrition
Hatchling varanids are ravenous feeders. It is virtually impossible to over feed a healthy, rapidly growing monitor. Every second day, hatchlings are fed a variety of food items. Their diet consists primarily of insect matter (crickets and cockroaches), but may be supplemented occasionally with 1 – 2 week old (pinky – fuzzy) mice.

When given the option, hatchling monitors will almost always choose large prey items over small prey items (relative to their body and head size). To the disbelief of many keepers, hatchling monitors of the subgenus odatria, can easily consume a very large (2/3” – 3/4”) cricket. They seem to ignore, or simply refuse to eat prey that is too small relative to their body size. Large prey items seem to stimulate a much more aggressive feeding response. Whether it’s due to the size of the target presented, or the faster movements of large prey, there appears to be a definite preference for more robust, live food items. It is also worth mentioning the importance of gutloading your feeders. Insect prey items should be fed a variety of fruits, vegetables and grains on a regular basis. When these insects are consumed, their stomach contents (gutload) are passed onto the monitor. When feeders are fed a variety of nutritious foods, the need for a multivitamin is greatly diminished. Monitors which are housed indoors and have no exposure to natural sunlight should be offered a calcium and vitamin D3 supplement on a regular basis. Vitamin D3 allows reptiles and other animals to metabolize calcium. UV radiation from the sun is a reptile’s primary source of vitamin D3. In the absence of natural sunlight, vitamin D3 must be supplemented.

Water is offered via a shallow dish. The dish should allow insects to climb out easily. Hatchling enclosures are sprayed lightly every 2-3 days. The substrate and cage furniture should appear dry within 4 - 8 hours after spraying. The frequency of misting will vary based on your local relative humidity. In regions of low relative humidity, keepers might be required to mist the enclosure more often. As a general rule, your enclosure should not appear wet. Excess water can lead to secondary health concerns.

Should hatchling varanids be housed individually, in pairs, or in small groups?
This is one of the most common questions asked pertaining to hatchling monitors. The answer is not simple, and can vary depending on species and the individual personalities of the monitors in question. One of the most common myths surrounding monitor colonies is that their sex is determined within the group and the most dominant animal will most likely turn out to be male. There is little evidence to support this theory and there are several other reasons that would explain the observed sex ratios experienced in captivity.

In our experience, there has been no significant difference in the sex ratios observed between animals raised individually or in groups. Reports of hobbyists raising a trio of animals to maturity (common accounts occur with V. a. acanthurus & V. a. brachyurus) and experiencing a sex ratio of one male and two females are extremely common. This observed sex ratio can be attributed to a couple of factors:

1) Monitors of the subgenus Odatria produce an unusually high number of female offspring. This has been the situation in our experience with most of the readily available “dwarf” monitor species in the reptile hobby. This general trend does not appear to apply to V. glauerti and V. pilbarensis, which have exhibited a fairly uniform sex ratio. Common incubation practices and temperatures may play a role in the gender trends observed with captive incubation (personal observation).

2) Keepers are unable to accurately determine the sex ratio of their monitor colony. Generally in this case, a keeper will have a trio of animals and report the dominant animal as the male and the rest of the animals as being female, even though this might not be the case. Often, subordinate or less dominant males will suppress their male characteristics and retain many feminine qualities. Not surprisingly, many keepers have no idea that their unproductive female is actually a subordinate male.

Therefore, it is not advised to group hatchling monitors under the premise of skewing the sex ratio in your favour. Keepers should not be afraid to house hatchlings individually. A solitary monitor will not always turn out to be male. The main reason for housing varanids in small groups should be to establish social hierarchy and group compatibility. There is no general rule for grouping animals that will encompass every species within the subgenus Odatria. Through observation, trial and error, several species specific rules have been formulated concerning the optimal number of animals that can be housed together for rearing purposes. The following table summarizes our recommendations, but as a general rule, the overall well being of each hatchling is greatly increased when there are fewer animals per cage.

Recommended Number of Inhabitants per Enclosure for Rearing Purposes

Animals / Colony
Compatability / Observations 

V. a. acanthurus
V. a. brachyurus

  * generally does well in pairs
  * if housed in trios, watch for excessive dominance behaviour and aggression
     (chasing, biting, etc.)
  * animals under stress will tend to grow slowly and   hide the majority of the time
V. caudolineatus
  * generally does well in pairs or trios
  * rare displays of dominance have been observed
 V. gilleni
V. glauerti
  * in general, hatchlings do poorly in trios
  * high stress levels have been observed with individuals in a group situation which can
     lead to loss of appetite, slow growth rate, tail kinking, and even death
  * outward signs of aggression are rarely observed between individuals
V. kingorum
  * does well in pairs
  * outward signs of aggression are rarely observed between individuals
  * symptoms of stress have been observed in trios
V. pilbarensis
  * refer to V. glauerti
V. storri
  * generally does well in pairs
  * violent aggression is common in animals that are not compatible which can quickly
     lead to the injury or death of an individual

V. t. tristis

V. t. orientalius

  * generally does well in pairs or trios
  * stress related problems are rarely observed
  * rare displays of dominance have been observed

Things to Consider when Housing Hatchling Monitors

Shedding and Toe Loss
Many keepers believe that when their monitor is in the process of shedding its skin, their enclosure should be misted heavily. In fact, the opposite is true. Unlike snakes, monitors do not shed their skin in one solid piece. Instead, a monitor’s skin flakes off in pieces over the period of a few days. Monitor skin easily flakes off when conditions are dry. But, when the enclosure is kept wet during this period, the skin does not flake off. Instead, the skin becomes saturated with water impeding the monitor’s ability to slough it off. This becomes a problem in areas such as the toes and tail. Unshed skin will form a ring around these appendages that will cut off circulation to that area. This happens once the skin has dried out and shrinks in size, or as the animal grows. Swelling of the distal portion of these appendages and toe/tail loss are all symptoms of previous or current exposure to high humidity levels.

©2009 Canadian Coldblood