This species occurs in northeast India, Bhutan, Nepal, and Bangladesh, throughout Southeast Asia, including Thailand, the Philippines, Malaysia and Indonesia, and to western New Guinea. Its native habitat is rainforest, where it lives on trees and cliffs, and it also frequently adapts to rural human habitations, roaming walls and ceilings at night in search of insect prey. This is an introduced species in some areas outside its native range. It is established in Florida in the United States, Martinique, the islands of Belize, and possibly Hawaii. Increasing urbanization is reducing its range.
It is currently unclear whether the species is native but very uncommon in Taiwan, or whether the rare reports of individuals since the 1920s are based on repeated anthropogenic translocations that may or may not have resulted in established populations by now.
The tokay gecko is a large. nocturnal gecko, reaching a total length (including tail) of up to 30 cm (12 in). It is believed to be the third largest species of gecko, after the Giant leaf-tail gecko (Uroplatus giganteus) and New Caledonian giant gecko (Rhacodactylus leachianus). It is cylindrical but somewhat flattened in body shape. The eyes have vertical pupils. The skin is soft to the touch and is generally gray with red speckles, but the animal can change the color of its skin to blend into the environment. The species is sexually dimorphic, the males being more brightly colored and slightly larger.
Tokay geckos are generally aggressive, territorial, and can inflict a strong bite. Females lay clutches of one or two hard-shelled eggs and guard them until they hatch. The tokay gecko feeds on insects, fruit, vegetation and small vertebrates. It is a strong climber with foot pads that can support the entire weight of the body on a vertical surface for a long period of time. Compared to other gecko species, the tokay gecko has a robust build, with a semi-prehensile tail, a large head and muscular jaws. Though common in the pet trade, the strong bite of the tokay gecko makes it ill-suited for inexperienced keepers. In addition, the strength of the bite depending on the gecko's size; larger (usually male) tokay geckos are capable of piercing skin, which often result in immediate bleeding.
The male's mating call, a loud croak, is variously described as sounding like token, gekk-gekk, tuck-too or poo-kay from which both the common and the scientific name (deriving from onomatopoeic names in Malay, Sundanese, Tagalog, Thai, or Javanese), as well as the family name Gekkonidae and the generic term gecko come. Most of the time, the call is often preceded by a quick "cackling", similar to the chirping sounds made by house geckos albeit much lower in pitch. When threatened or alarmed, tokay geckos usually "bark" while opening their mouth in a defensive posture.
The tokay gecko is culturally significant in many East Asian countries. Regional folklore has attributed supernatural powers to the gecko. In Southeast Asia it is a symbol of good luck and fertility. It is believed to be descended from dragons.
This species is poached for the medicinal trades in parts of Asia. The tokay gecko is an ingredient in Traditional Chinese medicine known as Ge Jie (). It is believed to nourish the kidneys and lungs, beliefs that are not substantiated by medical science. The animal remains highly sought after in China, Hong Kong, Taiwan, Vietnam, Malaysia, Singapore and other parts of Asia with Chinese communities, to the point where unscrupulous merchants have taken to disfiguring monitor lizards with prosthetics to pass them off as colossal tokay gecko specimens.
From 2009 to 2011 the poaching of Tokay geckos intensified due to a short lived belief that it was an effective HIV cure.
The tokay gecko is quickly becoming a threatened species in the Philippines due to indiscriminate hunting. Collecting, transporting and trading in geckos without a license can be punishable by up to twelve years in jail and a fine of up to Php 1,000,000.00 under Republic Act 9147 in addition to other applicable international laws. However, the trade runs unchecked due to the sheer number of illegal traders and reports of lucrative deals. Chinese buyers and other foreign nationals are rumored to pay thousands of dollars for large specimens, because of their alleged medicinal value or as commodities in the illegal wildlife trade.
Tokay geckos are becoming more popular as pets, due to their striking colors and large size. Most of them are wild caught imports, but captive bred ones are becoming more common. Wild caught adults can be difficult to keep due to their defensive nature and powerful bite, but captive bred babies can tame down if handled from a young age.
In captivity, tokay geckos eat commercially available insects, such as crickets, Dubia roaches, superworms, and mealworms. But some of them can also take premade diet replacements such as Grub pie.
The 18th meeting of the Conference of the parties to the Convention on International trade in Endangered species of Wild Fauna and Flora (CITES)took place in Geneva, there Gecko was included for the first time under Appendix II, means species under Appendix II are not necessarily threatened with extinction, but in which trade must be controlled in order to avoid utilization incompatible with their survival.
Two subspecies are currently recognized.