Pterois fish

Pterois is a genus of venomous marine fish found mostly in the Indo-Pacific, known collectively as the lionfish. Pterois is characterized by red, white and black stripes, showy pectoral fins and venomous spiky tentacles. Pterois are classified into fifteen different species, but Pterois radiata, Pterois volitans and Pterois miles are the most commonly studied. Pterois are popular aquarium fish and are readily utilized in the culinary world.

In the mid 1990s, the species P. volitans and P. miles were unintentionally introduced into the Atlantic Ocean and have become an invasive species along the East Coast of the United States.

Morphology and Behavior

Pterois range in size from 6.2 to 42.4 cm with typical adults measuring 38 cm and weighing an average of 480 g. They are well known for their ornate beauty, venomous spines and unique tentacles. Juvenile lionfish have a unique tentacle located above their eye sockets that varies in phenotype between species. It is suggested that the evolution of this tentacle serves to continually attract new prey; studies also suggest that it plays a role in sexual selection

Hazard to Humans

Lionfish are known for their venomous tentacles, a feature that is uncommon among marine fish in the East Coast coral reefs. The potency of their venom makes them excellent predators and dangerous to fishermen and divers. Pterois venom produced negative inotropic and chronotropic effects when tested in both frog and clam hearts and has a depressing effect on rabbit blood pressure. These results are thought to be due to nitric oxide release. In humans, Pterois venom can cause systemic effects such as vomiting, fever and sweating and has been lethal in a few cases.

Prey

According to a study that involved the dissection of over 1,400 lionfish stomachs from Bahamian to North Carolinian waters, Pterois prey mostly on small fishes, invertebrates and mollusks in large amounts, with some specimens’ stomachs containing up to six different species of prey. The amount of prey in lionfish stomachs over the course of the day suggest that lionfish feed most actively from 7:00-11:00 A.M., with decreased feeding throughout the afternoon. Lionfish are skilled hunters, using specialized bilateral swim bladder muscles to provide exquisite control of location in the water column, allowing the fish to alter its center of gravity to better attack prey. The lionfish then spreads its large pectoral fins and swallows its prey in a singe motion. Tiger grouper (Mycteroperca tigris) have been shown to occasionally prey on Pterois, but these findings have been few and far between.

Pterois can live from five to fifteen years and have complex courtship and mating behaviors. Females release two mucus-filled egg clusters frequently, which can contain as many as fifteen thousand eggs. Studies on Pterois reproductive habits are have increased significantly in the past decade.

Native Waters

The lionfish is a predator native to the Indo-Pacific. It aggressively preys on small fish and invertebrates. They can be found around the seaward edge of reefs and coral, in lagoons, and on rocky surfaces to fifty meters. They show a preference for turbid inshore areas and in harbors. Lionfish have a generally hostile attitude and are territorial towards other reef fish. Many universities in the Indo-Pacific have documented reports of Pterois aggression towards divers and researchers.