The Lionfish is one of the most venomous fish in the ocean. There are many species of Lionfish. The Red Lionfish is probably the most reconizable. This species can grow to a length of 17 inches long. The Red Lionfish is a popular species for saltwater fish tanks, but only for experienced ones. The Red Lionfish has spines that are all venomous. While nobody has ever died from a Lionfish sting, don't touch one. The sting of a Lionfish is very, very painful. The sting of a Lionfish can cause extreme pain, headaches, vomiting, and difficulty breathing. With this type of defense, the Lionfish has few predators.