The Reef Stonefish is the most venomous fish in the world. Its dorsal area is lined with 13 spines that release venom from two sacs attached to each spine. Its venom causes severe pain with possible shock, paralysis, and tissue death depending on the depth of the penetration. This level can be fatal to humans if not given medical attention within a couple of hours. Immediate first aid treatment requires immersion of the affected limb in hot water, ensuring that it is not so hot that skin damage may occur. The immobilisation of venom at penetration site by tourniquet or firm constrictive bandaging is no longer recommended.