Stonefish are considered the most venomous fish in the world. With an excellent ability to camouflage in rocky or muddy shallow ocean floors, these fish sport 13 defensive venomous spines on their back, each of which is like a hypodermic needle attached to a sac of venom, ready to cause severe harm to those who come into contact with them. Symptoms of a stonefish sting can include intense pain, swelling, tissue necrosis, and in some severe cases, death.
According to an article in Ocean Conservancy, "One victim wrote online (which was later reported by ABC News) that after being stung on the finger, it was like 'having each knuckle, then the wrist, elbow, and shoulder being hit in turn with a sledgehammer over the course of about an hour.'"
Getting stung by a stonefish sounds like a great way for a YouTuber to generate page views. That's exactly what Mark Vins (20.9 million subscribers) did when he went to eastern Australia to intentionally get himself stung by a stonefish.
In the video below, you can watch him look for a wild stonefish in the water, which isn't easy because it looks just like a moss-covered rock. Then he holds a piece of neoprene rubber against a few spines to show the surprisingly beautiful blue venom squirt from the tips. Before he stings himself, he explains that most people who die from stonefish stings do so from the shock of how painful this thing is, and not from the venom itself.
Before he lets the fish sting him, he tells viewers that stonefish venom quickly breaks down in the presence of heat. In his backpack, he has a thermos filled with hot water to pour on the bite in case the pain becomes too intense. He also has an EpiPen.
He then pushes his palm against one of the spines from which he had already extracted most of the venom so that he could give himself a "microdose" of stonefish venom. As soon as his hand touches the spine, he jerks it back involuntarily. Much of the rest of the video shows him wincing, grimacing, and complaining about how bad his hand feels. Even after he applies the hot water, he says the pain spreads all the way up past his shoulder and into his neck. A month later, he is still experiencing numbness in his hand and fingers.