Synanceia horrida, also known as the estuarine stonefish or regionally as simply stonefish, is a species of venomous fish of the family Synanceiidae. They are carnivorous ray-finned fish with venomous spines that lives on reef bottoms, camouflaged as a rock. They are one of the most venomous fish in the world, and are often included in private and public aquariums. The maximum length of the species is up to 60 cm (2 ft). It is drab in colour, brownish to reddish brown, which aids in its ability to camouflage itself among the rocks of many of the tropical reefs. It shares many characteristics with Synanceia verrucosa, but has more elevated eyes than that species. It has a sedentary habit, operating as an ambush predator, but can quickly open its mouth to gulp in its prey.It eats mostly small fish, shrimp and other crustaceans, waiting until its prey swims nearby.It was first described by Carl Linnaeus in 1766. The species is coastal areas of the Indo-West Pacific: India to China, the Philippines, Papua New Guinea and Australia, and is also recorded in Vanuatu. Its main habitat is on or near coral reefs or in estuaries, in marine or estuarine waters. It camouflages itself around dull coloured plants, near and about rocks, or found dormant in the mud or sand.