Possibly due to their starring roles in the 1960's Godzilla movies, the green iguanas (American iguana) that are found from southern Brazil all the way north to Mexico have become the most popular of all reptile pets. However, not only are these huge lizards poor pets, but the vast majority of owners who acquire them are not capable of providing the very specialized care they require. It is not an overstatement to say that the pet store industry has created a colossal catastrophe by irresponsibly selling green iguanas to unsuspecting admirers who are inexperienced, and ill-equipped.
Regardless of what some websites say, green iguanas are not for beginners. Many owners have been permanently injured by these reptiles, and an even bigger number of iguanas have been inadvertently killed by poor care-taking. Besides having complex environmental and dietary requirements, it takes time to bathe them, give them exercise, and prepare their meals. Green iguanas are a long-term commitment.
Common Name: Green iguana, American iguana
Scientific Name: Iguana iguana
Adult Size: Up to 20 pounds; 6 feet in length, the tail accounts for the majority of overall length
Life Expectancy: In the wild, green iguanas live about 20 years. Captive care can be challenging and many iguanas die within the first few years of life due to severe malnourishment and improper husbandry.
Green Iguana Behavior and Temperament
Green iguanas are diurnal (active during the day), arboreal (living in trees) large lizards that choose to inhabit trees near to and overhanging waterways. Iguanas are extremely good swimmers and will often choose to jump from a branch many stories high into a river splash-down to make a quick getaway.
These lizards grow to be very large extremely quickly, they do not like to be handled, and they have very dangerous claws and tails that are made for creating lashing injuries; they are not at all afraid to use them in the blink of an eye. When confronted, they are formidable fighters even as juveniles. They can inflict serious bites.
It takes them three to four years to reach adulthood. Juveniles stay in familial groups for the first year of their lives. Male green iguanas in these groups often use their own bodies to shield and protect females from predators (like hawks, owls, snakes, and humans), and they appear to be the only species of reptile to do this.
Housing the Green Iguana
A full-grown green iguana at six feet long needs more room than it does when it is young and only one foot long, but they do grow quickly. Most adult iguanas require half a small bedroom or a very large enclosure. Plan to construct an enclosure that is 8 feet long, 8 feet tall, and 4 to side feet wide, at a minimum.
If you can't let your iguana have its own bedroom in the house, you can build your own custom iguana cage or purchase an expensive custom-built enclosure. You must provide many hefty branches and perches to safely climb on, along with regular bathing opportunities and environmental elements. They also require specific heating and lighting elements.
Not commonly recognized, the green iguanas are native to the extreme, tropical environments; they require temperatures of 80 F to 95 F in order to be healthy. Supplemental heat should be offered by using heat lights and lamps but not heat rocks as they cause burns. Basking temperatures should be about 95 F, and the enclosure should never be allowed to drop below 78 F.
These lizards must have appropriate sources of UVB and UVA lighting. Otherwise, their bodies cannot produce vitamin D that promotes calcium absorption, which can result in metabolic bone disease (MBD), a fatal condition. UVB lighting should be on for 10 to 12 hours per day and the bulbs should be changed every six months, regardless of whether or not the light burns out.
These tropical lizards require high humidity. Add foggers or misters to separate locations in the enclosure to bring the average humidity up to 80 percent (a 70 to 90 percent range). Test the enclosure with a hygrometer in multiple locations, and bring all parts of the enclosure up to this range.
Food and Water
Many iguana owners are well-meaning but entirely misinformed about what iguanas need to be eating. Although green iguanas in captivity (especially the nutritionally deprived pets) will consume meat, excessive consumption of animal protein will result in severe kidney problems and premature death. Do not feed any meat to your iguana.
Being herbivores, wild green iguanas feed primarily on vegetables and fruits. Dark leafy greens should make up the majority of the daily diet, including dandelion greens, endive, kale, fresh parsley, mustard greens, arugula, and other calcium-rich leafy vegetables. Iguanas swallow their food whole without chewing, so chop all food items into small pieces. Feed this variety once per day; your iguana will not overeat. Remove and discard any food that hasn’t been eaten within 24 hours as all foods must be fresh to be accepted.
Misinformed iguana owners also tend to feed iceberg lettuce, which provides water, but has little nutritional value compared to other vegetables. Vegetables high in oxalates, such as calcium-binding spinach, should be avoided. Small amounts of fruits such as berries can be offered on occasion or to entice your green iguana to eat.
Provide a tip-proof water basin that is deep enough for your lizard to soak in but not large enough for swimming; change and clean the bowl daily. Iguana will sometimes learn to drink from a separate, clean and non-chlorinated water dish, however, they usually prefer to lap the droplets of water condensate from leaves or cage furnishings. Most of the iguana's hydration will come directly from the vegetarian diet.
Common Health and Behavior Problems
Being prone to several disease problems, iguanas in the captive environment are typically not healthy and robust pets. Watch your lizard closely for any signs of irregular or abnormal occurrences related to health.
If you see blood in your iguana's droppings, it may be from a bladder stone. An examination and radiographs (X-rays) will allow your veterinarian to diagnose this problem. Surgical removal of the stones is usually needed, as is fluid therapy to prevent kidney damage. Your veterinarian will discuss the necessary dietary corrections to prevent future stones from forming.
Swellings on the body are called abscesses. They are treated by surgical removal or lancing and flushing of the abscess. The material within the abscess can be cultured to identify the infective organism and to determine the treatment path.
Egg binding (dystocia) happens when a female is unable to pass her eggs. It is a common problem in captive reptiles but it can be life-threatening. Poor husbandry including improper lighting and temperature, wrong diet, and dehydration are common causes. An iguana with dystocia will be uninterested in food and become rapidly sick, lethargic, or unresponsive. Medical and surgical procedures are usually required to help these animals in order to prevent losing them.
Calcium is needed to help green iguanas grow, have strong bones, and avoid metabolic bone disease; vitamin D3 is needed to metabolize that calcium. Supplemental powders are available that can be dusted on the food at every other feeding. As your iguana grows, monitor the calcium and other chemistry values by having your exotics vet run some basic blood tests. These baseline values will let you know if you are providing enough, or too much calcium, protein, and other nutritional elements.
Choosing Your Green Iguana
Several dated online articles and books have incorrect information regarding their care, diet, and environmental requirements. Rely mainly on the expertise of scientific websites and the many iguana rescue organizations to learn about how to adopt an animal that is already in need of a home.
In some sensitive ecosystems, such as the state of Hawaii, iguana ownership is prohibited. They are exotic pets that have no natural predators on the island, so they are potentially hazardous to plant populations and to the insect and bird life the plants support. Due to the possible future impact from iguanas that have been set free by the owner after having grown too big for their owners to handle, the state of Hawaii strictly prohibits the import and possession of these tree-dwelling giants. Violators will spend three years in jail and be fined up to $200,000.
In New York City, ownership of these exotic lizards has been banned since 1999 out of a concern for public safety. They have been classified as animals that are wild, ferocious, fierce, dangerous, and naturally inclined to do harm to humans. The city's dense human population would all but assure unanticipated and unwanted human encounters associated with inadvertent enclosure escapes.
Similar Species to the Green Iguana
If you’re interested in the green iguana as a potential pet, review these other species of lizard:
Otherwise, check out other types of reptiles and amphibians that can be your pet!
Kubiak, Marie. Veterinary Care Of Green Iguanas (Iguana Iguana) Part 1: Husbandry. Companion Animal, vol 24, no. 7, 2019, pp. 386-389. Mark Allen Group, doi:10.12968/coan.2019.0023
Wanna Iguana? Do Your Reptile Research First! University of Illinois College of Veterinary Medicine, 2020
Management and Husbandry of Reptiles. Merck Veterinary Manual, 2020
Reproductive Diseases of Reptiles. Merck Veterinary Manual, 2020