Green Iguanas: The Basics

posted: 05/15/12
More Information[b]Iguanas & Other Lizards Main[/b], [b]Reptile Guide Main[/b]

Iguanas are becoming more popular as pets. Before getting an iguana, however, there are several things you need to seriously think about:

As with any pet, proper feeding, housing, and caring for your iguana is going to take time and money. Many diseases in iguanas are due to improper nutrition and environment. Do you know how to supply their basic needs?

Even with proper nutrition and housing, iguanas may develop health problems or become injured. Are you willing and able to provide the necessary health care for your iguana?

Iguanas grow. You may think the hatchling is cute, and easily housed in a terrarium. But, what are you going to do when the iguana reaches several feet in length, and needs a cage the size of a small room?

Origin of Green Iguanas

Green iguanas originate from the rain forests of northern Mexico to southeastern Brazil where the temperatures and humidity are high. Iguanas live in the trees and bask in the sun. They eat only vegetation: up to 50 different kinds of leaves, flowers, and fruits. Their captive environment must duplicate this as much as possible.

Green iguanas are egg layers. Like many turtles, the eggs are buried in the sand by the mother and once the eggs hatch, the hatchlings are on their own. They can grow up to 6 feet in length and weigh 18 pounds. With proper care, they may live 15 years or more.


Iguanas are cold-blooded and require supplemental heat for proper digestion. They prefer 84-90°F during the day and 70-77° at night. If a reptile is cold, it cannot properly digest its food and is more likely to become ill. Lizards like a temperature gradient so if they are cold, they can move to a warmer part of the cage and vice versa. Place a good quality thermometer in the cage at the level the iguana spends most of its time so you can monitor the temperature.

Primary heat source:

A primary heat source is necessary to keep the temperature of the entire cage within the proper range. A series of incandescent lights over the cage is one of the best heat sources. At night, these lights will need to be turned off and another heat source may be needed depending on the ambient temperature. A heating pad placed under the cage, ceramic infrared heat emitters or panels, or more expensive nocturnal reptile incandescent light bulbs which produce heat, but little visible light, can be used. For larger enclosures, a space heater or separate room thermostat can be used to keep the room at the appropriate temperature. Fire alarms should be placed in rooms where lights or other heat sources are used.

Secondary heat source:

A secondary heat source creates more heat in specific areas of the cage to provide a temperature gradient. To best supply this gradient, the secondary heat source should cover only 25-30% of the surface of the enclosure. The secondary heat source could be a 50-75 watt incandescent bulb in a ceramic base, securely mounted where the animal can not touch it. There are also special 'basking lights' available. Either type of light should shine down on a particular basking area from outside the cage. The temperature under the light in the area in which the iguana would be basking should be 90-100°F.


More on Light

Glass cages, even those with a screen top, should NEVER be used when providing access to natural sunlight. Glass cages will trap heat and can cause fatally high temperatures. Second to the sun, the best light source is a combination of visible light from fluorescent or incandescent lights, and UVB light from special reptile black lights or combination lights.


Visible white light: In addition to heat, incandescent bulbs also provide visible white light. A combination of fluorescent and incandescent light fixtures can be used to provide visible light to all areas of the enclosure.

Ultraviolet light: In addition to heat and white light, iguanas must have access to natural sunlight for good health. This is because they need a certain spectrum of ultraviolet (UV) light called UVB. UVB is necessary for the iguana to make Vitamin D. No artificial light is as good as sun in providing UVB, so when the outside temperature on a sunny day is over 70°F, place your iguana outside in a secure screen or wire cage with a locking door. Provide some shade and a hiding place within the enclosure. UV rays do not penetrate window glass so iguanas placed in a sunny window are not receiving UV light.

If an iguana does not have access to bright sunlight, special black lights are used to provide the UVB light. These black lights for reptiles are NOT the black light tubes used for lighting fluorescent minerals, posters, and psychedelic paraphernalia (often called BLB lights). Fish/aquarium and plant 'grow' lights, either incandescent or fluorescent, do NOT produce UVB. You need a black light, which emits light in the 290-320 nanometer range. Lights producing only UVB, and lights which produce a combination of UVB and white lights are available. ZooMed's reptile or iguana lights, and Durotest's Vita-Lite are two good products. These UVB light sources should be replaced every 6 months.

Remember that UV light can not penetrate glass, so when overhead UVB light sources are used, the top of the enclosure must be a wire mesh that is not too fine. It is recommended that the UVB light source should be less than 18 inches from where the iguana spends most of its time; 10-12 inches is optimal.

The areas illuminated by the incandescent basking light and the UV light should overlap. If the iguana spends almost all his time basking under the incandescent light, and the UV light is at the other end of the cage, he is not going to receive any benefit from it.

Photoperiod: Iguanas generally need 14 hours of light and 10 hours of darkness. The visible light and the UVB light source should be turned off at night to give the iguana a light-dark cycle. As mentioned above, supplemental heat may need to be added.

In summary, a variety of lights are needed, some for heat, some for white light and some for UVB light.

Water and Humidity

Fresh drinking water should be available at all times in a bowl that cannot be tipped over. Especially during the winter months when the humidity is low, mist the iguana with water several times a week. Most iguanas like to immerse themselves in water, so provide a larger container of water for bathing. Be sure the iguana is able to get in and out of the container easily. You will need to clean the container and replace the water regularly, since the iguana may urinate or defecate in the water. In fact, water usually stimulates them to eliminate, so immersing them in water is a part of the treatment for constipation.



Cages should be secure with tight-fitting lids. The sides should be smooth to avoid abrasions of the nose. Wire cages do not retain heat and can result in foot and nose trauma. Having a proper substrate in the cage (see below), and making sure the cage is large enough, and using plastic coated wire mesh can lessen the possibility of injury. Cages should be simple in design to facilitate cleaning. Cages made of wood must be sealed with polyurethane or a similar waterproofing agent and joints caulked to allow cleaning and disinfection. Fresh polyurethane must be allowed to dry several days and the cage thoroughly aired out prior to placing a reptile in the cage or toxicity may result.

Lizards require large cages to accommodate their active behavior. The cage should be at least as tall as the iguana is long (including tail); it should be 2/3 as wide as the iguana's length and 1-1/2 to 2 times as long. A 40-gallon terrarium with a screen lid will accommodate a young iguana. Since iguanas grow so fast, however, the larger the terrarium you can buy, the better. As the iguana grows and becomes longer than 3 feet, you will need something custom built. In warmer areas of the United States, large, outdoor, walk-in enclosures provide a good habitat.

Substrate: The substrate is what lines the bottom of the cage. An ideal substrate is one that is inexpensive, aesthetically pleasing, easily cleaned, absorbent, and digestible if swallowed. Substrate can be flat newspaper, sheets of brown wrapping paper (the kind that comes in rolls), astroturf, indoor/outdoor carpet, or alfalfa pellets. Do NOT use cedar shavings, gravel, crushed corn cob, kitty litter, wood shavings, or potting soil that contains vermiculite, pesticides, fertilizer, or wetting agents.

Landscaping and 'Furniture': Branches for climbing and basking under the secondary heat source should be secure. These branches should be of various sizes and not ooze pitch or have a sticky sap; oak works very well. The branches should be as wide as the width of the iguana. Boards covered with indoor/outdoor carpet also make good climbing posts. Flat-bottomed, smooth rocks are a good addition to the habitat, and can help wear down the toenails, which in captivity, must be clipped often.

Reptiles like a place where they can hide. This could be an empty cardboard box, cardboard tube, or flower pot. The hiding place should provide a snug fit and should be high in the enclosure. If your iguana does not use its hiding place try a different one or move it to a different location.

Appropriate plants in the enclosure can provide humidity, shade, and a sense of security. They also add an aesthetic quality to the enclosure. Be sure they are nontoxic. Dracaena, Ficus benjamina, and hibiscus are good choices. However, if you like hibiscus flowers, I will warn you, iguanas like them too - to eat. Be sure the plants have not been treated with pesticides and the potting soil does not contain vermiculite, pesticides, fertilizer, or wetting agents. Washing the plant with a water spray and watering it thoroughly several times to the point where water runs out of the bottom of the pot, should help remove toxic chemicals, which may have been used. Keeping purchased plants in a different part of the house for a while before putting them in the enclosure will also be helpful.


The cage and food and water bowls should be cleaned routinely with a 1:10 dilution of household bleach. Rinse the items well after cleaning. Iguanas can harbor the bacteria Salmonella. Be sure to wash your hands after handling the iguana or its cage.


Most iguanas will try to escape when you pick them up. Be sure your iguana is used to its cage and environment before you start handling it. Start handling the iguana at an early age. Take it slow - offer food from your hand, and repeat this several times a day. When the iguana accepts food regularly, you can start handling it. Give your iguana regular attention and be consistent in how you handle it. Use two hands to pick up the iguana, supporting its chest and pelvic area. It would rather hold on to you than have you hold on to it. Do NOT pick up an iguana by the tail; the tail may break off. Even though the tail will partially regrow, it will never look the same.

If You Have More Than One

Reptiles are territorial and may fight when caged together. During the breeding season males may kill each other or a male may pursue a female to the extent she cannot eat. Larger iguanas often keep smaller cagemates away from food and heat sources, and may even see them as an appetizer. A separate cage for each iguana is the best answer to these problems.

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