Scorpion Fish Facts (Scorpaenidae)

The lionfish is a good example of a type of scorpion fish.
The lionfish is a good example of a type of scorpion fish. Marcel Rudolph / EyeEm / Getty Images

The term scorpion fish refers to a group of ray-finned fishes in the family Scorpaenidae. Collectively, they are called rockfish or stonefish because they are bottom dwellers camouflaged to resemble rocks or coral. The family includes 10 subfamilies and at least 388 species.

Important genera include the lionfish (Pterois sp.) and stonefish (Synanceia sp.). All scorpion fish have venomous spines, giving the fish their common name. While stings can be fatal to humans, the fish are not aggressive and only sting when threatened or injured.

Fast Facts: Scorpion Fish

  • Scientific Name: Scorpaenidae (species include Pterois volitans, Synaceia horrida)
  • Other Names: Lionfish, stonefish, scorpionfish, rockfish, firefish, dragonfish, turkeyfish, stingfish, butterfly cod
  • Distinguishing Features: Compressed body with wide mouth and conspicuous, venomous dorsal spines
  • Average Size: Under 0.6 meters (2 feet)
  • Diet: Carnivorous
  • Life Span: 15 years
  • Habitat: Coastal tropical, subtropical, and temperate seas worldwide
  • Conservation Status: Least Concern
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Scorpaeniformes
  • Family: Scorpaenidae
  • Fun Fact: Scorpion fish not aggressive. They only sting if they are threatened or injured.

Description

The scorpion fish has a compressed body with ridges or spines on its head, 11 to 17 dorsal spines, and pectoral fins with well-developed rays. The fish come in all colors. Lionfish are brightly colored, so potential predators can identify them as a threat. Stonefish, on the other hand, have mottled coloring that camouflages them against rocks and coral. The average adult scorpion fish is under 0.6 meters (2 feet) in length.

Except for lionfish, scorpion fish have a mottled coloration that serves as camouflage.
Except for lionfish, scorpion fish have a mottled coloration that serves as camouflage. LITTLE DINOSAUR / Getty Images

Distribution

Most members of the Scorpaenidae family live in the Indo-Pacific, but species occur worldwide in tropical, subtropical, and temperate seas. Scorpion fish tend to live in shallow coastal water. However, a few species occur as deep as 2200 meters (7200 feet). They are well-camouflaged against reefs, rocks, and sediment, so they spend most of their time near the sea floor.

The red lionfish and common lionfish are invasive species in the Caribbean and Atlantic Ocean off the coast of the United States. The only effective method of control to date has been NOAA's campaign of "Lionfish as Food." Encouraging consumption of the fish not only helps control lionfish population density, but also helps protect overfished grouper and snapper populations.

Reproduction and Life Cycle

Female scorpion fish release between 2,000 and 15,000 eggs into the water, which are fertilized by the male. After mating, the adults move away and seek cover to minimize attention from predators. The eggs then float to the surface to minimize predation. Eggs hatch in after two days. The newly-hatched scorpion fish, called fry, remain near the surface until they are around about an inch long. At this time, they sink to the bottom to seek a crevice and begin hunting. Scorpion fish live up to 15 years.

Diet and Hunting

The carnivorous scorpion fish preys upon other fish (including other scorpion fish), crustaceans, mollusks, and other invertebrates. A scorpion fish will eat virtually any other animal that can be swallowed whole. Most scorpion fish species are nocturnal hunters, while lionfish are most active in the morning daylight hours.

Some scorpion fish wait for prey to approach. Lionfish actively hunt and attack prey, using a bilateral swim bladder to precisely control body position. To catch prey, a scorpion fish blows a jet of water toward its victim, disorienting it. If the prey is a fish, the jet of water also causes it to orient against the current so that it's facing the scorpion fish. Head-first capture is easier, so this technique improves hunting efficiency. Once the prey is positioned correctly, the scorpion fish sucks in its prey whole. In some cases, the fish uses its spines to stun prey, but this behavior is fairly uncommon.

Predators

While it's likely that predation of eggs and fry is the primary form of natural population control of scorpion fish, it's unclear what percentage of scorpion fish young are eaten. Adults have few predators, but sharks, rays, snappers, and sea lions have been observed hunting the fish. Sharks appear to be immune to scorpion fish venom.

Although scorpion fish are venomous, they are gentle animals. This diver is feeding a lionfish.
Although scorpion fish are venomous, they are gentle animals. This diver is feeding a lionfish. Justin Okoye / EyeEm / Getty Images

Scorpion fish aren't fished commercially because of the risk of stings. However, they are edible, and cooking the fish neutralizes the venom. For sushi, the fish may be eaten raw if the venomous dorsal fins are removed before preparation.

Scorpion Fish Venom and Stings

Scorpion fish erect their spines and inject venom if they are bitten by a predator, grabbed, or stepped on. The venom contains a mixture of neurotoxins. Typical symptoms of poisoning include intense, throbbing pain that lasts up to 12 hours, peaking in the first hour or two following the sting, as well as redness, bruising, numbness, and swelling at the sting site. Severe reactions include nausea, vomiting, abdominal cramps, tremors, decreased blood pressure, shortness of breath, and abnormal heart rhythms. Paralysis, seizures, and death are possible, but are usually restricted to stonefish poisoning. The young and elderly are more susceptible to the venom than healthy adults. Death is rare, but some people are allergic to the venom and may suffer anaphylactic shock.

Australian hospitals keep stonefish anti-venom on hand. For other species and for stonefish first aid, the first step is to remove the victim from water to prevent drowning. Vinegar may be applied to reduce pain, while the venom may be inactivated by immersing the sting site in hot water for 30 to 90 minutes. Tweezers should be used to remove any remaining spines and the area should be scrubbed with soap and water and then flushed with fresh water.

Medical care is required for all scorpion fish, lionfish, and stonefish stings, even if the venom appears to be deactivated. It's important to be certain that no spine remnants remain in the flesh. A tetanus booster may be recommended.

Conservation Status

Most species of scorpion fish have not been evaluated in terms of conservation status. However, the stonefish Synanceia verrucosa and Synanceia horrida are listed as "least concern" on the IUCN Red List, with stable populations. The luna lionfish Pterois lunulata and red lionfish Pterois volitans are also least concern. The population of red lionfish, an invasive species, is increasing.

While no significant threats face scorpion fish at this time, they may be at risk from habitat destruction, pollution, and climate change.

Sources

  • Doubilet, David (November 1987). "Scorpionfish: Danger in Disguise". National Geographic. Vol. 172 no. 5. pp. 634–643. ISSN 0027-9358
  • Eschmeyer, William N. (1998). Paxton, J.R.; Eschmeyer, W.N., eds. Encyclopedia of Fishes. San Diego: Academic Press. pp. 175–176. ISBN 0-12-547665-5.
  • Morris J.A. Jr., Akins J.L. (2009). "Feeding ecology of invasive lionfish (Pterois volitans) in the Bahamian archipelago". Environmental Biology of Fishes. 86 (3): 389–398. doi:10.1007/s10641-009-9538-8
  • Sauners P.R., Taylor P.B. (1959). "Venom of the lionfish Pterois volitans". American Journal of Physiology197: 437–440
  • Taylor, G. (2000). "Toxic fish spine injury: Lessons from 11 years experience". South Pacific Underwater Medicine Society Journal. 30 (1). ISSN 0813-1988