Green Iguanas

The green iguana is a lizard native to Central and South America. In their natural environment, iguanas are daylight active (diurnal) and dwell in trees (arboreal). Their day is spent foraging for food and basking in trees. With appropriate care, many captive iguanas can live 10–15+ years and reach 6 feet or more in length.

Housing is one of the first considerations in keeping your iguana happy. It is best to start with a high 20–29 gallon tank, but expect to purchase or build a larger cage in the future. Iguanas grow fairly quickly and under the right conditions, can grow to 2 feet in length at one year of age. As they continue to grow and mature, the adult iguana can develop to 6 feet in length and obviously will require a sizable enclosure.

Newspaper is an ideal cage liner since it is inexpensive and easy to clean. Astroturf (indoor/outdoor carpeting) also works well, but at least two pieces are needed; to allow for cleaning and drying of one piece while the other is in the cage. Alfalfa pellets (rabbit chow) can also be used in the bottom of the cage as a bedding material and may be safely eaten by the iguana. Bark, corn cobs, and cat litter should not be used, as they will cause intestinal blockage if ingested.

The cage should be cleaned as needed, which is usually on a daily basis, and disinfected weekly. Bleach diluted with water (2 tablespoons per gallon) is an appropriate disinfectant. Rinse thoroughly with water and let dry after disinfecting. Do not use Lysol as it is toxic to reptiles.

Visual security is desirable and can be accomplished using plastic plants, clay pots, cork bark, and other items that won’t be eaten. Large rocks also work well because they act as an abrasive surface that aids in removal of shedding skin. The iguana sheds its skin in patches, and the shedding frequency is determined by its growth rate.

Water is also an important aid in allowing the skin to shed. A shallow dish of water, or soak pit, is a necessity for smaller iguanas. The bathtub is a good alternative to use as a soak pit for larger animals. Misting with a spray bottle three to four times weekly can also help keep an iguana’s skin hydrated. Many times the soak pit is used as a toilet and must be kept clean. Clean drinking water must always be available, but many iguanas prefer to lap water droplets from plastic plants or other items in the cage when misted. Frequent misting can also help keep the humidity in the desired 50–75% range.

Climbing material is usually appreciated. Branches that reach up to the heat source are the preferred way to allow for basking. Make certain the lizard can’t get too close to the heat in order to avoid burns. Do not allow your lizard to roam your house unsupervised, as they seek out dark areas in which to hide and you may have trouble locating them when it comes time to return to their enclosure.

Providing your iguana with the correct environmental temperature range is important for normal activity and physiologic functions such as food digestion and maintaining a healthy immune system. A temperature gradient allowing for a warm area near the heat lamp and a cooler end away from the heat source is mandatory. This way, the lizard can choose the temperature it wants by moving about in the cage. The temperature should range from near 100°F at a basking site to about 75°F at the opposite end of the enclosure. For mature iguanas, the nighttime temperature can dip to 60–75°F.

The basking site is best provided by the use of a heat lamp. This can be an incandescent bulb; however, these cannot be left on 24 hours a day due to the white light that is emitted. This would mimic 24 hours of daylight and be stressful to the animal. Better alternatives are red heat lamps, black heat lamps for use at night, or ceramic heat bulbs that do not emit white light. All can be kept on for 24 hours to ensure the temperature doesn’t drop too low at night. To allow some cooling at night, the lamp can be moved farther from the cage.

The background temperature of the enclosure should be about 75°F. If the heat lamp doesn’t allow for this, then a second heat source is required. Under the tank heat is the preferred method, utilizing an appropriate reptile heat tape or heating pad. Thermometers are a must for monitoring the temperature both at the basking site (95–100°F) and the background temperature away from the basking site (75°F). It is also critical that the basking sight be far enough away from the heat source that it does not burn the iguana’s skin.

To help prevent metabolic bone disease (a common malady resulting in soft and easily deformed or broken bones), and to give your iguana a day/night cycle, it is important to supply it with “full-spectrum” lighting that provides an appropriate balance of ultraviolet light. Iguanas require a day/night cycle of about 14 hours daylight and 10 hours of darkness. This ratio can be reversed during the winter to provide 10 hours of daylight. Full-spectrum bulbs are made especially for this purpose. These lights cannot be covered by glass or Plexiglas, as this filters out the important ultraviolet rays. Screen is suitable to place between the light source and the lizard.

Full-spectrum lighting and the ultraviolet (UV) light it provides is also necessary for the synthesis of vitamin D, which in turn promotes calcium absorption from the intestines. A lack of UV light rays is the primary contributing factor in the development of calcium deficiency. Calcium deficiency and its resulting metabolic bone disease is one of the most common health problems in captive iguanas. Although there are a number of commercial full-spectrum bulbs available, there is no substitute for natural sunlight, unobstructed by glass. Even brief periods of time outside with exposure to natural sunlight can be equivalent to hours of basking under artificial lights. Therefore, during periods of warm weather, it is strongly suggested that you take your iguana outside for a nice bask in some real sunshine. Beware: It takes only a few minutes for the enclosure to become an oven, which will lead to hyperthermia (heat stroke) and sudden death. Only allow access to sunshine under direct supervision.

Iguanas are herbivores and appropriate dietary items include, but are not limited to, a combination of romaine and leaf lettuce (avoid head lettuce such as iceberg), spinach, broccoli, green beans, peas, alfalfa, parsley, lima beans, yams, rabbit pellets, corn, carrots, beet greens, alfalfa sprouts, kale, collards, mustard greens, escarole, zucchini, yellow squash, bok choy, Brussels sprouts, cabbage, and cauliflower. Fruits and berries can make up about 10% of the diet. These items include grapes, raspberries, melons, strawberries, peaches, banana, mango, kiwi, apple, blueberries, and cherries. Natural plants from your home or yard, such as nasturtium flowers, hibiscus flowers, and dandelion greens can also be fed as long as they have not been treated with any pesticides. Juvenile iguanas up to one year of age should be fed once or twice daily and adults can be fed daily (preferred) or every other day. Food items should be finely chopped and mixed thoroughly to promote ingestion of a variety of foodstuffs.

Iguanas may occasionally eat crickets as well as small rodents. Feeding crickets and other insects is not necessarily recommended; however, if fed, they should only be in limited amounts (up to 5% of the diet). It is also inappropriate to feed high protein items such as dog food, monkey biscuits, trout chow, cooked meats, and eggs. In addition, avoid cat food due to its excessive protein content.

The diet of young iguanas should vary somewhat from that of mature animals. This is due to their rapid growth rate and the need for increased calcium and protein. For juveniles, a powdered calcium-only (no added phosphorus please) supplement should be added in small amounts three to four times weekly and a multi-vitamin/mineral supplement (e.g., Herptivit) should be sprinkled on the diet two to three times per week. To reiterate, this involves purchasing two supplements: one multi-vitamin/mineral and one calcium-only supplement (e.g., Repcal) to be used on alternate days. As iguanas approach maturity at around 2 years of age, gradually reduce supplements to the point that calcium is added once weekly and the multi-vitamin/mineral is added once or twice weekly.

Commercial diets in the form of iguana pellets are also available and can be fed successfully. It is typically recommended to feed additional items from the above list for variety, water content, and completeness. Vitamin and mineral supplements should also be minimized when feeding commercial diets that are designed to be complete and balanced.

Following these guidelines and providing your pet iguana with appropriate lighting, environmental temperatures and humidity, and a balanced diet will all go a long way in ensuring you have done your best in keeping your pet healthy.