The Green Iguana (Iguana iguana) is truly a study in contrasts. Captive-bred by the millions on farms in Latin America, the 7-inch-long hatchlings are widely considered to be suitable for novice reptile keepers. Indeed, with proper care, they mature into one of the most impressive and responsive of all reptilian pets. Yet these tropical lizards have very specific needs that must be met if they are to thrive, and their eventual size (4-6 feet) and potentially aggressive behaviors are serious considerations.
Range and Habitat
The Green Iguana’s range extends from southern Mexicothrough Central America to Paraguay. They also inhabit Puerto Rico, St. Lucia and other Caribbean islands, and have been introduced to Florida and Hawaii (please see this article on Iguana-Raccoon Interactions in Florida).
Green Iguanas are always found near water, into which they plunge when frightened. They are often associated with forested areas, so I was surprised to encounter large populations in Venezuela’s treeless llanos region; please see this article.
Green Iguanas are ever-alert, and easily startled by noises, dogs and other threats. They vary greatly in personality – some become docile, while others remain wary of people.
Males may become dangerously aggressive with during the breeding season (please see article below), and either sex may bite, lash out with the tail, or scratch. The wound on my arm, pictured in the attached photo, resulted from a single flick of the tail (and my skin is generally described as “very leathery”!). Please write in for information on safe handling.
Setting up the Terrarium
Enclosure size is a major concern. Hatchlings will exceed 2 feet in length in their first year, and 3 feet by age 2. Adults reach 4.0 to 5.5 feet in length, with males sometimes exceeding 6 feet.
Hatchlings may be started in a 30 gallon aquarium, but will need a 55 gallon tank within 12 months. Once your lizard reaches 3 feet in length, a homemade or commercial cage will be necessary. An enclosure measuring 6 x 3 x 6 feet tall will suffice for an adult; wheels should be added to allow for sun exposure. Predator-proof outdoor cages such as modified bird aviaries are the ultimate in “luxury accommodations”.
Green Iguanas are highly arboreal and will be stressed if kept in enclosures that do not allow climbing opportunities. Stout branches and wooden shelves should be provided.
If an “iguana proof” room is available, out-of-cage exercise time can add greatly to your lizard’s quality of life.
Cypress mulch has been used with success, but impactions due to substrate ingestion are possible. Newspapers, washable cage liners or outdoor carpets are preferable.
Females without access to suitable nesting sites may retain their eggs; please see this article for information on captive breeding.
Green Iguanas will not thrive without a source of Ultra-Violet B light. Natural sunlight is best, but be aware that glass and plastic filter out UVB rays, and fatal overheating can occur very quickly.
If a florescent bulb is used (the Zoo Med 10.0 UVB Bulb is ideal), be sure that your pet can bask within 6-12 inches of it. Mercury vapor and halogen bulbs broadcast UVB over greater distances, and also provide beneficial UVA.
The ambient air temperature should range from 82-95 F, with a basking spot of 95-100 F. Incandescent bulbs should be used to maintain these temperatures. A ceramic heater or red/black night bulb can be used after dark.
Green Iguanas favor humidity levels of 65-75%, but must be able to dry off as well. The terrarium should be misted as needed. A reptile humidifier may be used in especially dry environments.
A large water bowl should be provided for drinking and soaking.
Males will fight savagely, and females may also battle for dominance. Juveniles usually get along, but must be watched carefully as they mature.
Strict attention to diet is essential if you are to succeed with Green Iguanas. Nutritional deficiencies can develop quickly, and are difficult to treat. Young iguanas should be fed daily; 2 small meals are preferable to 1 large. Adults can be fed every-other-day, or provided smaller daily meals.
Greens, Vegetables and Fruit
The majority of your iguana’s food – 60% or more – should consist of a variety of fibrous, calcium-rich vegetables such as kale, romaine, dandelion, bok choy, collards, mustard and turnip greens, beet tops and escarole; broccoli, peas, squash, beans, carrots, peppers and mixed frozen vegetables may be added in smaller quantities. Spinach binds calcium and should be avoided.
Fruit should not comprise more than 10% of your iguana’s diet. Bananas, pears, apple, figs, melons, berries, kiwi, peaches and others should be offered.
Boiled brown rice or fiber-rich, sugar free cereals (i.e. Fiber One) may be given as a fiber source. This may not be necessary if a variety of fibrous greens are provided, but serves well as “insurance”.
In their natural environment, young Green Iguanas consume both insects and vegetation before switching to a plant-based diet as they mature. While success has been had by using insects as a protein source for young iguanas, most keepers are better off relying upon legumes, such as boiled lentils or pinto, navy and kidney beans. These should make up 5-10% of the diet until age one, after which time they can be used as occasional treats.
A number of commercial iguana diets are available. While their long-term use as a sole diet has not been studied, adding some to your iguana’s salad should provide additional nutrients.
Most meals provided to growing iguanas should be powdered with a Calcium source such as Zoo Med ReptiCalcium. Reptivite or a similar vitamin/mineral supplements should be used 2-3 times each week. The supplementation needs of adults vary; please write in for further information.
Due to their size, Green Iguanas are sometimes allowed to wander at will about the home. While a room that has been carefully set up for your iguana (please write in for details) can be useful, free-ranging iguanas present serious health and safety risks. Chief among these are the potential for fires (dislodged lamps, etc.) and an increased risk of Salmonella transmission. Please write in for further information.
Aggression in Male Green Iguanas
Hawaii’s Green Iguanas and other Reptiles
Male Green Iguana during breeding season image referenced from wikipedia and originally posted by Cary Bass
This article although fine in some areas is extremely risky for any unresearched iguana owner.
It is imperative that Iguanas are kept fully away from animal protein, yes they would digest insects in the wild but only out of necessity if other forms of food are unavailable, in captivity that should never be the case and therefore they should never be offered, animal protein can cause long term damage that is completely un-noticeable until they reach older age. This is the same reason to keep away from processed Iguana foods as they usually seem to include some form of animal protein.
Iguana bodies / digestive systems are designed primarily and for the sole purpose of vegetation consumption and digestion, whilst the introduction of animal protein will not instantly kill your iguana, it will begin the processes of developing serious digestive issues later on in life, especially when an article like this is recommending the feeding of insects 3 times a week!
Thanks for your interest. Unfortunately, there is a good deal of misinformation circulating concerning iguana natural history and captive care. Iguana digestive systems have not evolved to digest plant foods alone. Youngsters are omnivorous, and utilize plant and animal foods effectively both in and out of captivity.
Adults, as mentioned, are primarily herbivorous. However, they remain able to digest animal based foods. For example, a recent study published in Herpetological Review (not available online, unfortunately) documented that adults in Guyana regularly visit Giant Otter latrine sites and consume feces left there. The undigested fish parts and bones likely provide Calcium, protein and other nutrients. This behavior may or may not be due to the fact that the nutrients are unavailable otherwise, but it appears significant that the study site is in prime iguana habitat. (However, as noted in the article, captive adult iguanas do not require animal protein when otherwise fed appropriately).
I realize that the flood of info available on the internet can be confusing, but I am basing my recommendations on 35+ years experience as a herpetologist in the field, with the Bronx Zoo, and in the private sector. Assuming that the diet is otherwise as described, the recommendations concerning insects can be relied upon with confidence.
Please let me know if you need any further information.
Best regards, Frank Indiviglio.
I am very sorry but the green iguana is definately 100% a herbivore lizard, the gut flora in their gut is designed to digest cellulose (fiber) something humans can’t.
They are hindgut fermentors which means their entire digestion is desgined to digest plant proteins, they require a rich caclium and fiber diet, the only reason an iguana will eat live food is as a one off freak occurence of oppurtunism, if an iguana came across a bit of droped sausage roll they would devour it as an act of oppourtunism, this doesn’t make it a right thing to feed inadequate husbandry or a terrotorial form of behavior, they get all the nutrients and moisture they require from the plant eating diet.
I have personally cared for iguanas suffering from renal failure or gout, and MBD whether that be by feeding crickets or pinkie mice the outcome can be the same and is easily avoided, you don’t need to be an “expert” to find the information and take in the basics of their biology, nutritional deficenciys is something that will happen by feeding a part or full live food diet and is easily avoided and prevented.
I use the considerd to be best vet in the UK aswell as have friends out there studying and researching wild iguanas at the minute, the beleif that iguanas eat live food is based entirely on as a bi – product of them eating foilage but a reminder is needed, captive iguanas certainly don’t live as long as what captive iggys do and this is likley a contributing factor, their are pleanty of papers and documents around of proffesionals supporting this idea, the live food issue is far outdated.
Thanks for your interest. Please see my response to the comment posted just prior to yours.
Unfortunately, the 3 major Herpetological Journals are not available online, except on occasion, but I’ll try to forward some relevant article abstracts if possible. In the meantime, this Herpetological Review article may be useful in providing some background…not re captive feeding guidelines, but just to provide a sense of their feeding ecology which is not well-covered elsewhere.
Best regards, Frank
I have recently launched a classified ad website for those wishing to purchase and sell exotic pets, including iguanas. I have been researching iguanas as a result. This article was an excellent primer/crash course for somebody like me who has little experience with this particular animal.
Thanks for the kind words, and good luck in your new endeavor, Best, Frank