Stonefish

The stonefish is one of the most venomous fish known that can be found in the Indo-Pacific waters.
The stonefish body is covered with encrusted brown or grey skin, with red, orange or yellow patches. It is a master of camouflage which makes it difficult to be noticed by divers.
Fortunately, the stonefish won't attack divers. The venom is used as a defense mechanism, being released when pressure is applied to its spine. Since it can stay out of water for up to 24 hours, it's not uncommon to see it lying on the beaches so be careful where you step.
A strange fact is that the stonefish is being consumed in some parts of Asia, such as Japan and China as the venom becomes harmless when heated.