Scorpionfish are a group of ray-finned venomous fish belonging to the large Scorpaenidae family.

Members of the Scorpaenidae family can be divided into 3 groups: lionfish (genus Pterois), scorpionfish (genus Scorpaena), and stonefish (genus Synanceja). Scorpaenidae stings are progressively more severe from lionfish to scorpionfish to stonefish (eg, lionfish spine injury typically causes localized symptoms such as blisters and inflammation, while stonefish spine envenomation can cause death).

The venom apparatus of fish in this family is composed of 12-13 spines of the dorsal fin, 3 spines of the anal fin, and 2 spines of the pelvic fin; these spines are grooved and contain venomous glandular tissue. Lionfish typically have long, relatively slender spines with the smallest venom glands and produce the weakest venom. Scorpionfish have shorter but sturdier spines and larger venom glands and, thus, have the potential to deliver a more potent sting. Stonefish have the shortest and strongest spines and the biggest venom glands and can deliver a much larger dose of far more powerful venom to a victim.

Scorpionfish are perch like and have well-camouflaged bodies allowing them to blend into their environment, making them very difficult to see in the water. They range in size from a few centimeters to half a meter (1.6 feet) long. The spines become erect if the fish is alerted, threatened, or touched. Species of this genus are found worldwide, in both the Atlantic and Pacific oceans. In the United States, scorpionfish are found around the Florida Keys, Gulf of Mexico, southern California, and in Hawaii.

Envenomation typically occurs when an unsuspecting swimmer steps on the fish. It can also occur during handling of the fish (eg, by fishermen).

When a scorpionfish spine punctures the skin of a victim, venom is released into the wound. The venom is heat labile and contains multiple toxic fractions. The wound area is initially ischemic and then cyanotic. Vesicles may form followed by tissue sloughing with surrounding cellulitis.

The severity of the sting depends on the size of the fish, the number of spines penetrating the skin, and other factors, such as body weight and health of the victim. Scorpionfish envenomation is very serious, causing intense, excruciating local pain that radiates throughout the affected limb.

Unlike most venomous fish, scorpionfish spine injury produces discrete alterations at the point(s) of puncture and can affect multiple body systems. Symptoms and signs include malaise, fever, local adenopathy, respiratory and cardiac alterations, hallucinations, and seizures. In a series of 23 injuries, all of the patients presented with intense pain and systemic alterations.

Systemic symptoms include nausea, diaphoresis, chills, muscle weakness, shortness of breath, hypotension, abdominal pain, and syncope. Late complications include paresthesias, secondary infection, ulceration, granuloma formation, and fibrous soft-tissue defects.