Have you ever walked into a pet store and looked at all the colorful marine fish? Chances are, you’ve probably had a lionfish catch your eye before. Lionfish are small to medium sized reef fish that can grow up to 19 inches in length and live up to 15 years old. These brightly colored wonders are a reddish brown with white stripes. These bright colors, although pretty, are aposematic colors, warning potential predators of their highly venomous spines located on their large ornamental fins. Lionfish are highly sought after aquarium fish because of their impressive fins and colors, native to the Indo-Pacific Oceans. Although lionfish are a gorgeous organism, their introduction to the United States has turned a beautiful fish into a major threat.

Lionfish were first noted in US waters in 1985 and their initial introduction is still a mystery to many scientists. Some believe that lionfish were introduced to the Gulf of Mexico after Hurricane Andrew destroyed an aquarium in Florida in 1992. However, this event took place 7 years after the first lionfish was noted in US waters. Others believe that they were initially introduced to dissatisfied aquarium owners discarding them into the ocean. Since their introduction, lionfish have been spotted all along the east coast of the US up to Rhode Island, right down to the Caribbean. The invasive populations are made up of two species, the Red lionfish (Pterolis volitans) makes up 90% of this population, while the very similar Devil Firefish (Pterolis miles) is also present. 

Lionfish have displayed many characteristics that favor their invasiveness. One of which is their large head with a large mouth, which makes them very effective predators of both fish and invertebrates. Lionfish also produce very rapidly, laying almost 1,000,000 eggs per year, and due to surface currents, are able to spread larvae very effectively. Also being a reef fish, lionfish tend to stick near structures such as jetties, oil rigs, coral reefs, and wrecks which are also home to many smaller marine organisms. They also have very few predators in their invasive range due to their venomous spines. An occasional shark or grouper may be able to prey on lionfish but for the most part, they are virtually apex predators.

Within their invasive range, there are 4700 reports of lionfish and they are able to live in densities five times that of their native range due to a lack of predation and an abundance of prey. Although lionfish haven’t quite reached a population size that can cause major ecological damage, there is concern that if that number is reached, serious ecological damages can occur (such as prey population collapse and reef deterioration). Lionfish are also very dangerous to humans. Lionfish stings generally aren’t fatal unless you are allergic, but in any case they can be extremely painful and should be taken seriously.

Many efforts have been instituted to attempt to control lionfish populations in their invasive range. A study in 2010 by James Morris, Kyle Shertzer, and James Rice projected that 27% of the adult population must be harvested monthly to control the populations. Since then, conservation groups in the Eastern US have organized lionfish hunting expeditions such as the “lionfish derby” in Florida held annually. Similarly, divers routinely spear lionfish during dives in the Caribbean. For deeper sections of water, vertical traps containing bait appealing only to lionfish are used to capture only the lionfish. Although lionfish are beautiful aquarium fish, they could be a major threat to their invasive ecosystems and this threat should continue to be monitored.