Green Iguana Care
Dr. Jenni Bass
80 to 95 percent dark leafy green plant material
Diet and Supplementation
Our understanding of the iguana's nutritional requirements has changed considerably over the last ten to fifteen years. Current studies will likely lead to further modification to current recommendations. The precise nutritional requirements of the green iguana are not known. For this reason, one must adhere to certain principles based on their known biology when feeding iguanas.
A single commercial or restricted homemade diet can be dangerous. Iguanas are true herbivores; more specifically, they are folivores (leaf eaters). Although their requirements change slightly as they age, the bulk of their diet should always be dark leafy greens, high in calcium and high in fiber. Since we cannot offer the leaves found in the iguana's natural environment, every effort must be made to select from what is available. Offer as wide a variety as possible of foods of the highest nutritional quality.
What follows are recommendations based on clinical experience, common sense and sound research:
5 to 20 percent other vegetable matter
No more than 5 percent of the diet should be fruit, as it is low in calcium and high in energy. If offered high calorie foods, iguanas eating to meet their energy requirements may not eat enough to meet their other requirements, such as for calcium.
No more than 20 percent of the diet should be protein, with no or restricted use of animal protein.
As iguanas age, their protein requirements decrease. The following is a guideline for healthy iguanas, growing normally:
Up to 12 to 18 months old; usually less than 30 cm, nose to vent: Feed 15 to 20 percent protein; feed hatchling iguanas twice daily and juvenile lizards daily. A variety of healthy foods, appropriately high in calcium are crucial if metabolic bone disease is to be avoided.
12 to 24 months old; snout to vent length usually 30 to 45 cm: Feed adolescent iguanas daily, but decrease protein to 10 to 15 percent.
Over two years old; snout to vent length usually greater than 45 cm: Mature iguanas can be fed daily or every other day, with less than 10 percent protein. It may be easiest to offer protein just once a week. Obesity is a common problem for captive animals that do not have to move more than a few feet to find an abundance of food.
Cat food or dog food is never appropriate for iguanas, as they cannot digest it properly and it can lead to serious nutritional deficiencies and toxicities. Meat products are often high in fat, vitamin D and phosphorus and low in calcium. Cat food, dog food, other meats and monkey chow should never pass green lips.
Use vitamin and mineral supplements cautiously, as there is a very real risk of overdosing vitamins A and D. Remember that supplementation will not compensate for a poor diet. A multivitamin/mineral supplement designed for reptiles can be given weekly to young iguanas, every two weeks to adolescent iguanas and monthly to mature iguanas. In addition, a calcium carbonate or calcium gluconate supplement, containing no vitamin D or phosphorus (purchased from a pharmacy) is recommended every two to three days for young lizards, every three to four days for adolescent lizards and weekly for mature animals. It is a good idea to discuss the topic of supplementation with your veterinarian, in light of the rest of the iguana's diet and his health status.
The following are suggested food sources for iguanas. Every effort should be made to offer foods high in calcium as the bulk of the diet, and at least two of these should be included in every feeding. A variety of other foods in the proportions discussed above, should also be provided. Foodstuffs should be washed, mixed, and if the lizard is a picky eater, should be chopped as finely as necessary or run through a food processor to ensure that he does not eat just his favorite things. In the case of young lizards, offer a variety of foods from the beginning to develop healthy eating habits.
Suggested vegetable sources, relatively high in calcium include: dandelion flowers and greens, beet, mustard, collard or turnip tops and greens, alfalfa pellets or grass, timothy hay, Swiss chard, escarole, parsley, spinach, romaine lettuce, broccoli leaves (not florets), cilantro, hibiscus leaves, mulberry leaves, and Chinese greens.
Suggested vegetable sources, lower in calcium include: hibiscus, nasturtium, rose and carnation and other edible flowers (be sure that these have not been treated with artificial colors or pesticides), clover, watercress, savoy cabbage, kohlrabi, sprouts, asparagus, peppers, sweet potato (cooked), kale, carrot, squash, bok choy, corn, thawed frozen vegetables.
Suggested fruits include: figs, grapes, papaya, raspberries, mango (these fruits are relatively high in calcium as compared to the others), melon, apricot, dates, peach, prune, raisin, berries, pear, plum, kiwi, apple and banana with skin.
Note that grapes, banana, spinach, beets, cabbages, Brussels sprouts, broccoli, bok choy, kale and cauliflower should be fed in moderation as they can interfere with calcium metabolism.
Suggested protein, grain and fiber sources include: soaked dry legumes (kidney, navy, mung beans, etc.), commercial reptile diets, natural bran cereals and whole grain breads.
Tofu is high in plant fat, and so should be fed in moderation, if at all.
Commercial diets are a convenient option when feeding iguanas, but it must be emphasized that these diets are a relatively recent creation, and are subject to minimal regulations with respect to content. Food colorings, preservatives and many other ingredients would never cross an iguana's path in the jungle, and so it is recommended that none of these diets form the majority of the diet until further research has been done.
A further concern with formulated diets is that they are dry. Some pelleted diets may be soaked, but should not be dripping, as important nutrients may leach out. Low grade, long term dehydration is a common problem for captive iguanas, so it is important that food be moist and that clean water be available at all times. Clean the water dish daily, and check it more often, as many lizards will urinate and defecate in their water dishes. Ideally the dish should be large enough to allow the animal to soak, but must be easily entered and exited.
In addition to providing water and maintaining a humid environment, it is a good idea to soak your pet at least twice a week. Iguanas are natural swimmers and should be allowed to express this natural behavior. Soaking will encourage urination and defecation, and so can become a means to keep the cage clean. Iguanas can also be misted – at least once a day is best. This may help to stimulate the appetite as well as to increase humidity.