How big does a green iguana actually get, and is my house ready for that?

Green iguanas are among the largest lizards commonly kept as pets, with wild and captive adults regularly reaching 4 to 6 feet in total length, including the tail, and weighing 8 to 18 pounds depending on sex and diet (San Diego Zoo Wildlife Alliance, n.d.). Because more than half of that length is tail, owners often underestimate how much horizontal and vertical space the animal needs — a full-grown iguana requires an enclosure many times larger than what stores sell for hatchlings, often custom-built rather than off-the-shelf.

University of Florida IFAS Extension notes that green iguanas can reach sexual maturity and near-adult size within 2 to 4 years, which is often when owners are caught off guard by the space, heat, and cost the animal now demands (University of Florida IFAS Extension, n.d.). A realistic enclosure for an adult is frequently described in reptile husbandry literature as needing to be at least 12 feet long, 6 feet wide, and 6 feet tall — closer to a walk-in closet than a glass terrarium — which is a major reason so many iguanas are rehomed.

What does a green iguana eat, and can I really keep it on a plant-based diet?

Green iguanas are strict herbivores in the wild, and captive diets should mirror that: a base of dark leafy greens such as collard, mustard, and turnip greens, supplemented with other vegetables and a smaller portion of fruit, according to the Merck Veterinary Manual (Merck Veterinary Manual, 2023). Owners sometimes offer animal protein like eggs or crickets believing it helps growth, but Merck's veterinary reference specifically warns that high-protein diets are linked to kidney disease and gout in iguanas, making strict herbivory a health requirement, not just a preference.

Calcium-to-phosphorus balance matters as much as ingredient choice. Because captive iguanas fed unsupplemented produce commonly develop metabolic bone disease, most care guides recommend dusting food with a calcium supplement without phosphorus several times a week and providing UVB lighting so the animal can synthesize vitamin D3 to actually use that calcium (Merck Veterinary Manual, 2023).

What kind of lighting, heat, and humidity setup does an iguana enclosure need?

As a tropical species, green iguanas need a basking spot around 95 to 100°F and an ambient daytime temperature in the mid-80s°F, dropping no lower than the mid-70s°F at night, along with humidity in the 65-75% range to mimic their native rainforest and riverside habitat in Central and South America (Merck Veterinary Manual, 2023). Both a heat source and a dedicated UVB bulb are non-negotiable — UVB output degrades over months even when the bulb still lights up, so reptile veterinarians generally recommend replacing tubes every 6 months regardless of appearance.

Because iguanas are arboreal, the enclosure needs sturdy branches and shelving positioned near the basking light rather than floor space alone, and enough vertical height for the animal to thermoregulate by moving up and down. Owners who use screen-only enclosures or standard household lighting typically cannot hit these temperature and UVB targets, which is a leading contributor to metabolic bone disease diagnosed in pet iguanas.

How can I tell if a green iguana at a store or breeder is actually healthy?

A healthy juvenile iguana should have bright, clear eyes, a rounded (not concave) body, straight limbs, and a firm jaw without swelling — a soft or rubbery lower jaw is a classic early sign of metabolic bone disease from calcium deficiency, according to husbandry guidance from the Merck Veterinary Manual (Merck Veterinary Manual, 2023). Buyers should also ask to see the animal move: iguanas with MBD often drag or favor limbs, and severely affected animals can have visibly bowed legs or a kinked tail.

It's worth checking the source's setup rather than just the animal. A dealer or breeder keeping iguanas in overcrowded tubs without visible UVB lighting or a thermal gradient is a red flag, since animals raised without proper lighting from hatching are more likely to already have subclinical bone disease that won't show obvious symptoms for weeks. Reputable reptile breeders and rescues will typically let a buyer see the housing conditions the animal came from.

Are green iguanas dangerous to keep around kids or other pets?

Green iguanas are not venomous, but adults have a strong bite, sharp recurved claws, and a tail they can use as a whip in self-defense, and unneutered adult males in particular can become notably more aggressive and territorial during breeding season, per reptile behavior guidance summarized by the Merck Veterinary Manual (Merck Veterinary Manual, 2023). Bites and deep scratches from an adult iguana are common enough in reptile-owning households that most care sheets recommend against unsupervised handling by young children.

There's also a documented public-health angle: like most reptiles, iguanas can carry Salmonella bacteria in their gut without appearing sick, and the CDC specifically advises against keeping pet reptiles in homes with children under 5, elderly residents, or anyone with a weakened immune system, along with routine handwashing after handling the animal or cleaning its enclosure (Centers for Disease Control and Prevention, 2023).

How long will I need to care for a pet iguana, and what does that commitment involve?

Well-cared-for green iguanas commonly live 15 to 20 years in captivity, which is longer than many dogs and far longer than most first-time reptile owners anticipate when buying a hatchling (San Diego Zoo Wildlife Alliance, n.d.). That timeline means the enclosure, lighting replacement schedule, and vegetable-heavy grocery routine aren't a short-term project but a recurring monthly cost and chore for two decades.

Because of this mismatch between cute hatchling and demanding adult, green iguanas are among the most frequently surrendered reptiles at rescues and sanctuaries, several of which report waiting lists of unwanted adult iguanas needing rehoming. Prospective owners should treat that surrender rate as real data about the species' difficulty rather than an argument that any individual owner will be different.

Should I get my iguana from a breeder, a pet store, or a rescue?

Because so many adult iguanas are surrendered once they outgrow starter tanks, reptile rescues and herpetological societies frequently have adult or juvenile iguanas available at low or no cost, already past the fragile hatchling stage and sometimes already accustomed to handling. Adopting an existing adult also sidesteps the biggest hidden risk of buying a hatchling: not knowing what husbandry, if any, it received in its first months.

If buying from a breeder or store instead, prioritizing a seller who can describe their UVB and temperature setup, and who keeps animals in visibly clean, appropriately sized enclosures, matters more than price. The Association of Reptilian and Amphibian Veterinarians and general veterinary guidance both stress that establishing a relationship with a veterinarian experienced in reptile medicine before or immediately after acquiring the animal is part of responsible sourcing, since general small-animal vets may not be equipped to diagnose iguana-specific issues like MBD or renal disease (Merck Veterinary Manual, 2023).