Reef stonefish are the most poisonous fish in the world. Stonefish live in warm, tropical waters, primarily in the Oceanic region of Australia and New Zealand. They have 13 long spines in their dorsal fins that are filled with highly toxic venom, which the stonefish use to kill prey.
Two species of stonefish exist in Australia: reef stonefish and estuary stonefish. They look quite similar in appearance, although they have different eye positions, which is their sole distinguishing feature. A deep, centered depression separates the eyes of reef stonefish, while the eyes of estuary stonefish are slightly raised and separated by a bony ridge.
In addition to packing poisonous venom, stonefish have the ability to change color to blend in with their surroundings. They appear as brown or gray in color and may have patches of red, orange and yellow. These fish reside along coral reefs: they congregate toward the bottom of reefs, making their homes under rocky ledges and outcroppings. Stonefish may also bury themselves in the sand, where they lie in wait for passing prey. Stonefish feed primarily on fish and crustaceans such as lobsters, shrimp, crabs and crayfish. They attack humans when frightened or threatened. Doses of injected venom are not always fatal, but they often leave victims in excruciating pain.