A lionfish with its venomous spines flared out
Lionfish have eighteen spines that they use for self-defense, and each is filled with venom. Image: Wai Siew / Unsplash

Named for their flowing fins, lionfish have made an epic journey from their native Indo-Pacific to the Atlantic, where they now thrive as an invasive species.

I met my first lionfish in the Virgin Islands, where they are invasive. Because of this, we were allowed (and encouraged!) to find, kill, and eat lionfish. Our biology team dissected the lionfish we caught to assess the health of the lionfish, and to catalogue the type and amount of fish that it had eaten. 

Regardless of whether you see them in their native or invasive range, lionfish are a majestic fish with a list of impressive traits.

What is a Lionfish?

“Lionfish” are a group of twelve carnivorous fish species that can live in a variety of marine habitats. They’re part of the scorpionfish family, which means that they also possess venomous spines.

Where Do Lionfish Live?

Lionfish are native to the South Pacific and Indian Oceans (Indo-Pacific). They appeared along the southeastern coast of the United States around 1990, and officially established in the Caribbean in the early 2000s.

What do Lionfish Eat?

Lionfish are generalists, which means that they eat many different types of marine animals – fish, mollusks, shrimp. Lionfish have also been known to be cannibalistic, with larger lionfish actually preying on smaller lionfish. They have massive appetites; their stomachs can expand up to 30 times the normal size.

A lionfish opening up its mouth.
What do lionfish eat? Image: Vlad Tchompalov / Unsplash

Are Lionfish Poisonous or Venomous?

First, what is the difference? Poison is ingested, inhaled, or absorbed, and venom is injected. Lionfish have eighteen spines that they use for self-defense, and each is filled with venom. They have a combination of colors that means “warning” in the animal kingdom: contrasting stripes of maroon and white.

If you see a lionfish flaring its spines out, then it’s best to back away!

Lionfish Sting Treatment

Their venom has a neurotoxin in it that can cause pain, swelling, respiratory distress, and paralysis in humans. This venom acts on the nerve cells that sense and relay pain to our brain, and this may be what makes the sting so painful.

Lionfish aren’t aggressive by nature, but in the event that you get accidentally stung by a lionfish, here are some steps you can take:

  1. Remove any visible spines from your skin 
  2. Clean the area (soap and freshwater, or antiseptic towelettes)
  3. Apply direct pressure with a clean cloth to control bleeding
  4. Help the venom break down with hot water (for 30-90 minutes)
    • Do not burn yourself; this will make the injury worse. Water at a temperature of 48.9°C (120°F) will work.
    • after 90 minutes, let the area return to normal temperature and then an ice pack can be used to help reduce swelling 
  5. Take over-the-counter pain medication
  6. Apply a topical antibiotic cream to reduce infection risk
  7. If needed, seek medical attention. 
    • Not all lionfish stings require medical attentions. If the pain is severe, seek medical attention as soon as possible to avoid more serious side effects.

The best thing to do is to be proactive – be on the lookout, respect your surroundings, and give any lionfish you see some space.

A lionfish camouflaged against the bright coral.
Watch your surroundings when snorkeling or diving with lionfish. Image: Anna Ortega

Are Lionfish Invasive and Why?

Their arrival in southeastern Florida – an area to which they are not native – makes them invasive. “Invasive species” often has a negative connotation because these species may alter the food chain, but invasive simply means not native.

Read More: The Top 5 Most Invasive Ocean Species 

How did the lionfish population become so successful as invasive species? It’s a combination of a few things:

  1. No natural predators
    • Now some species are learning that they can eat lionfish, and the lionfish populations are becoming part of the food chain.
  2. Abundant food sources
    • The Caribbean waters are highly biodiverse, and lionfish are generalists.
  3. Insanely high reproductive output
    • Females reach sexual maturity at 1 year old, and from this point can release 50,000 eggs every three days.

How did Lionfish get to Florida? 

Theory A) Boat ballast tanks picked up lionfish/eggs in the Indo-Pacific and when they dumped ballast water in the Caribbean, they introduced lionfish to the ecosystem.

Theory B) Lionfish are part of the aquarium trade, so they could have been in aquariums and accidentally washed out to sea when Hurricane Andrew hit in 1992… or intentionally released by owners who didn’t know the potential future consequences.

Scuba diving with lionfish.
Lionfish are an enticing sight for snorkelers and scuba divers. Image: Anna Ortega

Can you Eat Lionfish?

Lionfish can be eaten and is delicious. Eating lionfish has been encouraged since the lionfish invasion started, in an attempt to get people to remove lionfish from the reefs to mitigate the impact of these animals on the environment. 

However, even though the invasive Caribbean lionfish started as unwelcome guests, the population is slowly becoming part of the ecosystem. Lionfish are beautiful, resilient creatures who thrive in many locations – making them an enticing sight for snorkelers and scuba divers.

To learn more about Anna Ortega and her role as a marine science teacher in the British Virgin Islands, read her story here!

Anna grew up far away from the ocean, but that hasn’t stopped her passion for marine science. She is a marine biology graduate student at the University of Western Australia, spends her summers as a marine educator in the Caribbean, and studied spotted eagle ray behavior in the Meso-American reef.