Iguanas make great pets -- but only for certain people. I would not recommend them to the average pet owner. There are many easier care lizards out there. Unfortunately iguanas are also one of the most neglected and in need of adoption and rescue. So many people dump them when they get big, and in terribly poor health.
4 to 6 feet is pretty typical, depending on gender. They all get big. Not only do they have huge size requirements, but they have many other specialized requirements, including UV full spectrum lighting and heating.
One of the main problems is building a huge enough cage that also provides them with the proper lighting. This is why free-ranging iguanas is problematic. UV lightbulbs have a very limited range. The good spectrum is only within a certain distance of the bulb. Therefore, for example, hanging them on the ceiling and then letting the iggie run around the room just won't work. Without the proper lighting, they can get metabolic bone disease and many other problems.
They also need tropical temperatures, with basking spots, all carefully regulated in terms of heat.
All that AND tons of space and exercise!
Also, their primary diet is fruits and veggies. Lots and lots of fresh veggies. It needs to be prepared every morning. Some people just aren't up for that.
In terms of the diet, it's terribly sad that it's still perpetuated. They are indeed vegan, like guinea pigs. It is all traced back to a single sentence by a guy named Swanson who was simply guessing, and hadn't put any research into it. Now, so many books on iguanas contain the information that is directly contradicted by research and study of iguanas.
Animal protein and green iguanas
"For years, it was thought that iguanas were omnivores, consuming both animal and plant matter. While there have been some observations of some individuals eating insects and carrion, most have occurred in places where iguanas have colonized nonnative habitats, or in highly disturbed native habitats. Long term research into many different populations has shown that this is not a species-wide behavior in iguanas in their native habitats."
"The only sentence in Swanson that refers to juveniles is: 'Very young iguanas are probably almost entirely insectivorous, but I have made no personal observations on their feeding habits.'"
https://www.anapsid.org/pdf/onepageigcare.pdf
Iguanas: Your iguana came from one of many countries in Central and South America
"Despite the information commonly found in the pet literature, field and lab research has repeatedly shown that iguanas are not omnivores - the are strictly herbivorous and should be fed as such in captivity."
The Iguana Den - Iguana Diet
The Iguana Den - Iguana Diet - What Not To Feed
"1. Animal protein of ANY kind - cat or dog food, meat, cheese, insects, money biscuits, etc. Iguanas are obligate herbivores. Their bodies physically cannot process animal proteins. Feeding animal proteins puts a huge strain on the kidneys and liver and lead to an early death from kidney or liver failure."
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"Iguanas are strict herbivores.Although many iguana care books and a few people still recommend iguanas be fed insects and other animal protein based foods, the Green Iguana Society would like to stress that iguanas are strict herbivores (plant eating only). The myth that iguanas in the wild have been seen eating insects can be explained in a number of ways, but the fact is that they usually only eat insects in the wild by accident along with a piece of vegetable matter or by necessity when no other foods are available."
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Unfortunately, this has been repeated over and over as fact rather than speculation, leading to poor iguana husbandry.
Some of those sites have forums. They have tons of great information.
