Green Iguana — care sheet

Advanced. Green iguanas are one of the most commonly surrendered reptiles in the world, and it is almost always for the same reasons: people underestimate the size, the cost, and the sheer amount of space an adult needs. This is a two-metre, multi-decade, room-sized commitment with strict UVB, heat, humidity, and diet needs. Wonderful for a dedicated advanced keeper who plans for the full-grown animal from day one; heartbreaking as an impulse buy.

100% herbivore (folivore). The whole diet is plants: roughly 60-70% dark leafy greens (collard, dandelion, mustard greens, turnip greens, kale in rotation, escarole, watercress), about 20-30% other vegetables (squash, bell pepper, green beans, snap peas, grated carrot), and only about 10% fruit as a treat (berries, mango, papaya). NEVER feed animal protein, insects, dog or cat food, or "monkey biscuits." This is critical: iguanas are strict vegetarians in the wild, and animal protein is a leading cause of fatal kidney disease and gout in captive iguanas. Offer fresh food daily and remove uneaten produce before it spoils.

Adults need a custom, room-sized, VERTICAL enclosure, not a fish tank. Plan for a minimum around 10 ft long x 5 ft wide x 6 ft tall (3 x 1.5 x 1.8 m); an ideal build is closer to 12'L x 6'W x 6'H. As a rule of thumb, length should be at least twice the iguana's body length and height at least 6 ft, because these are arboreal climbers who need to get UP. Fill it with sturdy, thick climbing branches and broad basking shelves that can hold a 15-20 lb animal, plus solid smooth walls (no wire mesh they can rub their snouts raw on). Because iguanas soak and even swim, include a large, shallow water/soak area big enough to fit the whole body, at room-to-lukewarm temperature; change it daily and disinfect weekly. Hatchlings can start in a temporary 20-55 gallon setup but will outgrow it within a year, so budget for the adult space before you buy.

A hot basking surface of about 120°F (50°C), measured at the branch or shelf with a temperature gun (not a stick-on dial). This gives them a proper spot to thermoregulate and digest.

Ambient/cool end around 75-85°F (24-29°C), so the animal can move down the gradient to cool off.

Should not drop below the low-to-mid 70s F; keep nights roughly 73-84°F (23-28°C). A gentle nighttime dip is fine, but never let it get cold.

STRONG UVB is non-negotiable for this rainforest baskers. Use a high-output linear T5 HO tube (e.g. Arcadia 12-14% or Zoo Med Reptisun 10.0), spanning much of the enclosure, mounted so the basking zone reads a UV Index (UVI) of about 3.0-4.0. With mesh in the path, that is roughly 13-24 inches from the animal depending on the bulb, so measure with a Solarmeter rather than guessing. Run it 10-13 hours a day and replace tubes on schedule (about every 6-12 months) since UV output fades long before the light dies.

Fairly humid, reflecting their tropical origins: aim for roughly 60-80% during the day, with a higher spike toward 100% at night (misting or a humid microclimate). Chronically dry air contributes to poor sheds, dehydration, and kidney strain. Provide good airflow too, so damp does not become stagnant.

Use a safe, absorbent substrate: a 2-4 inch (10-15 cm) layer of large-particle coconut husk or cypress mulch works well for holding humidity, or go simple with pelleted paper bedding or reptile carpet for easy cleaning. Avoid loose sand, fine particles, pine, and cedar (impaction and respiratory irritation risk). Spot-clean daily and refresh regularly.

Because captive greens rarely match wild browse, dust food with a calcium supplement and use a reptile multivitamin. A common schedule for growing iguanas is plain calcium (no phosphorus) several times a week plus a multivitamin a couple times a week; adults need less. An all-in-one herbivore supplement (e.g. Repashy SuperVeggie) at meals is a convenient option. With proper UVB you generally do NOT need heavy D3 dosing, but calcium is essential to prevent metabolic bone disease. When in doubt, ask your exotics vet to tailor the schedule.

Very large. Males commonly reach 6-7 ft (1.8-2.1 m) total length including the tail; females rarely exceed 5 ft (1.5 m). A big adult weighs roughly 15-20 lb (about 7-9 kg). Much of that length is tail, but the body alone is substantial and heavy.

15-20+ years is normal with good care, with exceptional well-kept individuals reaching into the low 20s. Sadly most captive iguanas die far younger from preventable husbandry failures (kidney disease, metabolic bone disease). This is a decades-long commitment on par with a dog or cat.

See a reptile or exotics vet if you notice: Swollen, stiff, or painful joints; reluctance to move, eat, or drink (possible gout, often diet-related) — see an exotics vet.; Soft, rubbery, or bowed jaw/limbs, tremors, or a spongy 'rubber jaw' (signs of metabolic bone disease) — urgent vet visit.; Not eating for several days, sudden weight loss, sunken eyes, or lethargy (possible kidney disease/dehydration) — see a vet promptly.; Straining, a female who stops eating and seems restless or bloated (possible egg-binding) — this is an emergency.; Increased or absent urates/droppings, or chalky white deposits, and any labored breathing or open-mouth breathing — see an exotics vet.; Persistent stuck sheds around toes/tail (constriction can cost a digit), or wounds, abscesses, or a rubbed-raw snout from cage rubbing..