The lionfish is a living room showpiece, striped maroon and white with long fanlike fins. Released into the Atlantic, it has become one of the ocean’s most destructive invaders. Native to the Indo-Pacific, it carries 18 venomous spines for defense and hunts by hovering motionless, then blowing jets of water that spin small fish around to face it head first so they can be swallowed whole. At home, moray eels, large groupers, and other predators keep it in check. In the western Atlantic, the Caribbean, and the Gulf, almost nothing recognizes it as food.

This episode traces how the invasion happened and why it has been so hard to stop. The popular story blames Hurricane Andrew for smashing an aquarium in 1992, but the first documented Florida sighting was at Dania Beach in 1985, and genetic testing points to the aquarium trade and fish from the Philippines. Lionfish tolerate cold, near fresh water, and depths of 300 meters, and one female can release up to 2 million eggs a year that drift on ocean currents. Spearfishing has made the survivors warier, so people are turning to traps, robots, and the dinner plate.

• A single lionfish on a native coral reef can cut the population of juvenile reef fish by 79 percent.
• A 2010 study found that culling alone would have to remove 27 percent of the adult population every month to keep numbers under control.
• Engineers are building remotely operated vehicles such as a prototype called the Reef Sweeper, which uses a harpoon gun at depths divers cannot reach.
• NOAA launched its Lionfish as Food campaign in 2010, and once the spines are removed the meat is safe and compared to grouper or snapper.
• In Colombia, Catholic priests urged parishioners to eat lionfish on Fridays during Lent and at Easter, and consumption spiked.