Last time you went to an aquarium, you probably saw a lionfish swimming happily in a tank filled with a bit of coral or rocky bottom, calmly flipping its fins about in the slight current created by the water pump. Now think back to the interpretive sign next to the tank – did it say that the exhibit displayed an invader or an awesome, weird aquarium fish? Depending on which part of the world you’re in, you might get a different answer. Along the east coast of the United States, though, it should say the former. Lionfish have spread from south Florida throughout the Caribbean and up to North Carolina, where they can be found on reef habitat (either natural or manmade via the sinking of ships) at a concentration of 400 fish per square meter. And they eat everything in sight.