Tegus are members of the Teiid family of
lizards, and are closely related to the
North American Whiptails (Cnemidophorus
species) and the Latin American Jungle
Runners (Amieva species). In
appearance and habits, the Tegus mimic the
African and Asian Monitor Lizards, thought
they are not closely related. This is an
example of what biologists refer to as
"convergent evolution," in which organisms
from different groups evolve towards the
same body plan and habits in response to
similar environmental niches.
Taxonomically, the Tegus are the subject of
much debate. There are at least three
recognized species of Tegu. The most highly
prized is the Red Tegu, Tupinambis
rufescens, which is found in the
northern part of Argentina. The Black and
White Tegu, Tupinambis teguixin, is
native to Argentina, Brazil and Uruguay. It
is not often seen in captivity. The most
common Tegu found on dealer lists is the
Black Tegu, Tupinambis nigropunctatus.
The Black Tegu is found throughout the
Another variant of T. nigropunctatus
is the Gold Tegu (shown above), once
considered to be a separate species but now
classified as a geographical race of the
common Black Tegu. It has a black and yellow
pattern, with the most sought-after
individuals being almost pure yellow or tan.
Tegus (the name comes from a Latin-American
Indian word for "lizard") are large and
powerful animals with a reputation for
aggressiveness. The Red Tegu is the largest,
but ironically is also reputed to be the most docile.
The Gold Tegu is generally held to be the
most aggressive--but this seems to be more a
matter of individual temperament than
overall species behavior.
A full-grown male Tegu will typically reach
a length of 3 to 3½ feet, and weigh around 8
pounds. (The largest Tegu known was just shy
of 5 feet long, and weighed over 15 pounds.)
Although some individual lizards will adapt
to the human presence and be more or less
amenable to handling, most will be difficult
to handle, and are capable of delivering
punishing tail slaps and deep scratches, as
well as nasty bites. Even a "tame" Tegu can
turn on its keeper in an instant if it is
startled or spooked. None of the Tegu
species is suitable for the beginning herper.
A large number of Tegus are imported into
the United States each year from Latin
America. Nearly all of them, however, arrive
only as skins, which are widely used in the
leather trade to produce "alligator"
wallets, shoes, and belts. A single adult
Tegu skin can bring an Argentine farmer
almost as much money as he can make in a
month's wages. In their native Latin
America, Tegu tails and legs are also highly
prized as food.
Tegus require spacious, sturdily-built
cages. Juveniles will require at least
20-gallon tanks. Adults will need
specially-built cages--the minimum size for an
adult lizard is 4' x 4' x 3', and bigger is
better. These active lizards will utilize
every square foot of space that you can give
them. Since Tegus have powerful legs and
claws, any accommodations will have to be
tough, and able to withstand a lot of abuse.
A securely locking lid is an absolute must--Tegus
are very good climbers, as well as
astonishing leapers. An adult lizard can
easily get over a three or four foot
Although female Tegus may sometimes share a
cage together without complaint, males will
be aggressive towards each other. Even if
they "get along," these active lizards may
still accidentally injure each other with
their sharp claws. It is recommended that
these lizards be housed individually.
A large water dish or pool is necessary.
Tegus are excellent swimmers, and sometimes
like to soak and bathe. In the wild, they
are seldom found far from a water source,
and their preferred habitat consists of
heavy jungle along rivers or streams. Since
Tegus seem to prefer to defecate in water,
the water pan in their cage will have to be
The substrate for a Tegu tank must be chosen
with practicality uppermost in mind. It will
have to be changed often. Some substrates,
such as pine shavings, crushed corn cob, or
aquarium gravel, should be avoided. If the
Tegu accidentally swallows any of these
substrates, it can produce an intestinal
impaction or blockage that can have fatal
consequences. Some keepers use reptile bark
or aspen chips in their cages.
Shredded coconut bark is another excellent choice, because it
can be used dry or moist--and will not turn moldy when wet.
Ordinary utility carpet mats can also be
used; these have the advantages of being
inexpensive and easy to clean. Simply
brush off uneaten food or feces, and run
them through your washing machine when they
become heavily soiled.
Tegus are tropical animals, and require warm
humid conditions. Daytime temperatures
should be in the high 70's to low 80's,
dropping to the mid-70's at night. Since
Tegus are, like all reptiles, exothermic,
temperature control is one of the most vital
factors in keeping them in captivity. Nearly
every potential health problem that these
lizards face can be directly traced to how
well their temperature requirements are
being met, and probably more captive Tegus
are killed by being kept at a too-low
temperature than any other cause.
The cage must also be well-ventilated.
Screened areas at the cage top and bottom will provide a proper
air flow, but these should
be located where the lizard cannot reach
or it may rub its nose raw on the wire. In
home-built wooden cages, a series of
ventilation holes can be drilled along the
top and bottom edges.
The best setups will provide a range of
different temperatures, or a "temperature
gradient," within the cage, allowing the
Tegu to select the temperature that it wants
by moving from warmer to cooler areas as
The electric "hot rocks" or "sizzle stones"
which are often sold in pet stores should
never be used. The cheaper ones usually do not
have any means of controlling the heat
output, and thus there is no way to regulate
the temperature. They are also prone to
malfunctions. Since lizards have few nerve
endings in their bellies, they will often
sit unknowingly on an overheated hot rock,
completely unaware that their skin is being
severely burned. This can lead to
severe injuries and death.
Another problem is that sizzle stones do not
warm the surrounding air very much, and only
heat one small spot in the tank. They do not
provide a usable temperature gradient, and
do not allow the lizard to effectively thermo-regulate.
The best way to set up a Tegu's basking spot,
and provide it with necessary UVA/UVB at the same time, is to
buy a multi-purpose incandescent heat bulb such as ZooMed's
PowerSun, and mount it outside
of the cage, at one corner of the screen
Like all diurnal (active during the daytime)
lizards, Tegus need access to unfiltered
ultraviolet light. Reptiles use the
ultraviolet wavelengths in sunlight to
manufacture Vitamin D3 in their skin. This
vitamin is essential for proper bone
development. Lack of UV light causes serious
skeletal illness which is usually fatal.
(Please note that both glass and plastic block the useful UV
rays, so your UVA/UVB bulb should be used with screening rather
than glass or plastic.) It is also helpful to provide your
Tegu with as much unfiltered natural sunlight as possible, by
taking it outside for periods of time on warm days.
A flat pile of rocks should be arranged
directly below the basking spot. The basking
light thus produces a localized "hot spot"
for basking, while leaving the far end of
the tank relatively unheated. The Tegu can
then warm up when it needs to by following
its natural behavior pattern--it looks for a
warm sun-baked rock to rest on.
A very useful arrangement is to connect the
basking light to an electrical timer, to turn it on and off
automatically. A light schedule of twelve hours on, twelve hours
off, which mimics the length of the tropical day, is best.
Tegus are large active predators, and will
eat virtually any animal they can overpower.
They track their prey with their long forked
tongue, which transfers scent molecules to
the Jacobson's Organ in the roof of their
mouth in a manner similar to snakes.
Juvenile Tegus will do well on a diet of
crickets, provided these are "gut-loaded"
and/or dusted with vitamin and calcium
powder. Even young lizards have large
appetites, and can easily put away 75 or so
crickets a week. They will also accept
pre-killed pinkie mice.
Adult Tegus can be fed a staple diet of
whole pre-killed or frozen-and-thawed
rodents. These can often be simply dropped
into the cage, or offered in a food dish. If
your Tegu prefers its prey to be moving, it
can be jiggled on the end of a pair of long
tongs or forceps (NEVER feed a large Tegu by
hand, unless you want your nickname to
become Three Fingered Louie).
Most Tegus will also accept eggs, which make
up a large part of their diet in the wild.
There is some reason to believe that
unfertilized eggs may be harmful to large
predatory lizards over the long term. To
play it safe, it is best to offer eggs only
as an occasional treat.
Most authorities consider Tegus to be
omnivorous; they will, on occasion, accept a
piece of fresh sweet fruit, such as banana
or melon, that is placed in their food dish.
Handling a large Tegu can be an adventure,
to say the least. Wild-caught adults are
irascible and mean, and usually never lose
their fear of humans. Captive-bred animals
and younger wild-caught can be tamed
somewhat, depending on individual
temperament. However, great care should be
taken around even "tame" Tegus, as they are
very fast, very excitable, and can inflict a
respectable amount of damage on the unwary
Young animals should be handled often, to
accustom them to the process while they are
still too small to effectively object and
inflict any serious damage. If gently
handled for fifteen or twenty minutes every
day, a young Tegu will come to learn that
humans are not a threat, and will learn to
As soon as you approach a captive Tegu, you
are likely to hear a series of short
"huffs." The frequency of the
tongue-flicking will also increase as the
Tegu tries to assess the situation. This is
a sign that the lizard is nervous or
excited, and although it doesn't necessarily
mean the Tegu will try to bite, it does mean
that it's not happy with the situation and
needs to be watched carefully.
If further excited, the lizard will often
raise itself up on its legs and swell out
its chest in an attempt to look
intimidating. As a final warning, it may
face the intruder and gape its jaws widely
to display the sharp conical teeth. A
tail-lashing usually follows, and, if all
else fails, a bite.
When handling a large Tegu, the first
priority is to control the tail.
Gently grasp the base of the tail, near the
vent, with one hand, at the same time
gripping one of the rear legs between the
fore and middle fingers. Lift up a bit so
the rear feet are off the ground (this
prevents the lizard from turning quickly)
and slide your other hand, palm up, along
the belly until you reach the front legs.
Pin one of the front legs between the fore
and middle fingers (your forefinger should
encircle the neck just behind the jaws and
the lizard's chest should lie in the palm of
your hand). Lift the lizard and pin its tail
between your arm and upper body. Use the
fingers of one hand to control the neck and
front legs, and use the other hand to press
the back legs down along the tail. This will
allow you to carry the lizard without risk
from the tail, claws, or teeth.
To make handling easier, the Tegu's nails
should be periodically trimmed. This can be
done using the commercial nail clippers sold
for dogs or iguanas--the ones that look like
a short pair of scissors with a half-moon
shaped cutting area. Nail-trimming a large
Tegu is a two-person operation. One person
holds the lizard and controls it, the other
does the actual clipping. Only the very tip
of the nail should be trimmed; if you cut
too close to the base of the claw, it will
bleed, and your Tegu will be VERY annoyed.
A Tegu's claws should be trimmed every month
Tegus are not often bred in captivity. In
the wild, breeding takes place in the fall.
As is typical with most lizards, mating is a
rather rough affair, with the male grasping
the back of the female's neck in his jaws
before twining his tail with hers. Gravid
Tegu females use their powerful claws to dig
a shelter (sometimes they rip open insect
nests) and lay 4-6 eggs there. The newly
emerged hatchlings are about five inches
long, and have a protective coloring pattern
of greenish gray with darker spots. They
assume their adult colors after about four
The Tegu is not as commonly found in
captivity as are the more popular Monitors.
This is unfortunate, since it is an
attractive, intelligent, and fascinating
animal with a definite "personality." When
kept by an experienced herper who is
prepared to meet the requirements and
responsibilities of owning a large
potentially-aggressive lizard, the Tegu can
be a worthwhile addition to any collection.