 De Vosjoli writes that captive animals have been known to survive and thrive on eating nothing but whole rodent block, or monkey chow, and one instance of romaine lettuce with vitamin and calcium supplements.However, it is only recommended that captive iguanas not be fed lettuce or meat, and instead receive the vitamins and minerals they need via a purely herbivorous diet.The American pet trade has put a great demand on the green iguana; 800,000 iguanas were imported into the U.S. in 1995 alone, primarily originating from captive farming operations based in their native countries (Honduras, El Salvador, Colombia, and Panama).