Stonefish are located primarily within the Indo-Pacific oceans, while there are some species which live in rivers. These fish are equipped with deadly dorsal fins which are like needles, they can secret some extremely poisonous neurotoxins. The results of a sting can be deadly if left untreated. Even if treated, the stings have an excruciating pain as well as large swelling for months, it can also cause the tissues around the stung area to die.