The red lionfish (Pterois volitans) is a venomous coral reef fish from the Indian and western Pacific Oceans. The red lionfish is also found off the east coast of the United States, and was likely first introduced off the Florida coast in the early to mid-1990s. By the summer of 2001, it was found along the Atlantic coast of the United States from Florida to Long Island, New York. The Caribbean is also suffering from an invasion, especially around the Bahamas.

Red lionfish have distinctive red, maroon, or brown and white stripes; fleshy tentacles above the eyes and below the mouth; fan-like pectoral fin; and long separated dorsal spines. Adults can grow as large as 17 inches (43 cm), while juveniles may be as small as an inch or less. All of the spines on a lionfish are venomous, creating a danger primarily to divers and fishermen if stung. Although there have been no known fatalities caused by lionfish stings, they are reportedly extremely painful.

These juveniles were about 2 inches long by about the same across.

Red lionfish (juvenile).
Pterois volitans
The National Aquarium, Plymouth.