Iguanas have been around as pet reptiles for a very long time. When people first started keeping them as pets they were cared for much differently then they are now.
Like most exotic pets, we learn more about them as we go. Therefore, several older online articles and books have incorrect information regarding their care, diet, and environment requirements. It is crucial to the well-being of your green iguana to provide the most current recommendations for care that there are. If you aren't sure if the information you are reading is correct, one obvious red flag to alert you to an outdated article or book is the recommendation to feed animal proteins to your green iguana. Anything that says animal protein is what your iguana needs (i.e. dog or cat food, mice, etc.) is wrong. By feeding a green iguana animal protein you are destroying their kidneys. Iguanas cannot properly break down that type of protein.
Another red flag would be the lack of UVB lighting. More recently UVB lighting has become more common place among reptile owners but there was a time when very few indoor reptiles had the UVB rays that they need.
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 malnourishment and improper husbandry.
Green iguanas can grow to be up to 20 pounds. They will reach about 6 feet in length, including their tail which accounts for the majority of their overall length.
Being herbivores, green iguanas feed primarily on fruits and vegetables. 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. 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.
Heating and Lighting
Green iguanas are from tropical environments. Supplemental heat should be offered using heat lights, not hot rocks. Basking temperatures should be about 95 degrees Fahrenheit and the tank should never drop below 75 degrees Fahrenheit.
UVB lighting should be on for 10-12 hours a day and the bulbs should be changed every 6 months, regardless of whether or not the light burns out. Mercury vapor bulbs are excellent for very large enclosures, such as entire rooms, while smaller compact or tube fluorescent bulbs are adequate for a juvenile enclosure.
Calcium is needed to help green iguanas grow, have strong bones, and avoid metabolic bone disease. Vitamin D3 is needed to metabolize the calcium. Supplemental powders are available that can be dusted on the food at every other feeding. As your iguana grows it isn't a bad idea to monitor the calcium and other chemistry values by running some basic blood tests with your exotics vet. These baseline values will let you know if you are providing enough, or too much calcium, protein, and other vital elements.
A full grown green iguana obviously needs more room at 6 feet long than it does when it is young and 1 foot long, but they do grow fast. Most adult iguanas require half a small bedroom, or one heck of a large enclosure. Things to climb safely on must be provided, along with regular bathing opportunities and heating and lighting elements. Many people end up building their own custom iguana cage or purchasing a fancy custom built one if they don't let their iguana have his own bedroom in the house.
Regardless of what some people and websites tell you, green iguanas are not for beginners. They require specific heating and lighting elements, a lot of space, and daily fresh food cut up for them. They need your time to bathe them, give them exercise, and prepare their meals. And they live for about 20 years. Green iguanas are a long-term commitment so if you aren't good with reptile relationships, you'd better pass on this one.