Netherlands Antilles Coral Reef Initiative

last updated: May, 2010


Why are lionfish so bad?

Lionfish are invasive fish. They are not native to the Caribbean reef ecosystem and therefore not subject to ecological controls, allowing them to spread uncontrolled. They are voracious and indiscriminate predators, meaning that they eat anything. Any kind of fish, crab, shrimp or lobster small enough to swallow (and they can swallow things up to two thirds of their own size) is fair game to them. Their prey is defenseless because they do not even recognize lionfish as a threat and they are not used to their way of hunting. As a result lionfish are expected to have very bad effects on the local fish populations. This has been verified by one study in the Bahamas by Albins and Hixon who found that the presence of one lionfish on a small patch reef was sufficient to reduce recruitment of young reef fish by 79%.

Why should we be catching these beautiful fish?

If left unchecked lionfish will multiply and devour most other fish, leaving only themselves, lots of them. Photo

Because lionfish are an invasive species, they disrupt the local ecosystem. They are a very hardy fish that breed quickly and in large numbers, voracious predators that never stop eating, and they will overrun our reefs if we do not control their numbers. However beautiful they are, they are a dangerous menace that will eventually destroy the local ecosystem if left unchecked, as all invasive species do, leaving nothing but themselves in very large numbers (examples are rabbits in Australia, water hyacinths choking waterways in Africa and southern USA, casuarina forests in Bermuda, the devastation in Lake Victoria of almost all local cichlid fish by the introduction of the Nile Perch, etc.). Literally the only way to prevent them from completely overrunning our reefs is to keep their numbers as low as possible, and that means catching them in an all out effort that needs everyone's participation. Right now, when you only see one or a few of these beautiful fish you may wonder why we should kill them, but in only a few years these few will become ten or twenty and all you will see during a dive will be (albeit beautiful) lionfish.

What's the point in catching them, we can't eradicate them anyway?

It is correct that we cannot eradicate lionfishes. Young lionfish arrive with the ocean currents which we cannot stop; they live at depths down to 150 m, far beyond where we can dive; this makes it impossible to kill them for good, they would simply return from the deep or reach the island again from other places. However, we do not need to eradicate them completely to prevent them from destroying our reefs. Especially on our islands where we have many divers visiting dive spots all along the leeward shores, it is quite feasible with enough support from everyone, to keep their numbers down locally. In effect we can create sanctuaries around popular divesites where other fish will have a chance to grow and breed without the threat of lionfish predation.

What are their natural enemies where they come from?

It's not quite clear what the natural enemies are of the lionfish in the places where they are indigenous.More than likely there will not be one particular enemy. When a species is native and embedded in the local ecosystem there are usually various checks and balances that regulate its numbers. These checks and balances might range from a particular fungus or bacteria that attacks its eggs, predation of the larvae when they float in the ocean currents, predation on juvenile or small adult specimens, or a parasite that infects adult fish. So even if some of the larger predators in the Caribbean (almost all gone because of overfishing) learn to prey on lionfish, this will likely not be enough to control their numbers. The only thing that is likely to have an impact on lionfish numbers is if we humans become their enemies and start preying on them.

Can't we introduce a disease to kill them all?

Biological control can often be one of the most effective ways to combat invasive species, and this can consist of the introduction of a disease or parasite that specifically targets the invaders. However, this is also a very dangerous weapon and extreme caution is needed befoer using it. A disease killing lionfish is highly likely to also kill other fish, since most fish diseases are not species specific. The last thing we would want to do is introduce a cure against lionfish that would be worse then the orginal problem. The research to identify a very specific control agent against an invasive species is difficult and very expensive, usually only cost effective when the invading species causes huge economic damage by impacting agriculture for example (weeds), and not usually even begun unless in the face of such direct economic losses.

What should I do if I'm stung by a lionfish?

Lionfish venom is a protein that is destroyed by heat, so the best remdy is to immerse the wound in hot water or another liquid as hot as you can stand (you should not burn yourself). If you go lionfish hunting, bring a thermos with hot water with you just in case (tea, coffee or soup will also do the trick). If you don't have that, you can heat a wet towel or rag on the hot motor block of your car and then put in on the wound. Failing that, look around for a piece of metal that has been lying in the hot sun and use that.
If this does not help, or not enough, your hand or arm swells up greatly and the pain is unbearable, go to a doctor or hospital for a morphine shot and antihistaminic treatment if necessary. Some people may experience an allergic reaction and have trouble breathing; seek emergency help as soon as possible

Aren't lionfish poisonous to eat?

No, Lionfish are venomous, not poisonous, meaning that they have to inject you with venom for it to have an effect. Just like snake or scorpion venom it has to enter your blood stream before it has an effect. Poison on the other hand is something that needs to be ingested or inhaled. Pufferfish ('Fugu', treasured in Japan as a dangerous delicacy) are poisonous, they have a substance in their liver and other organs that kills you when eaten. The venom of a lionfish, if eaten, is simply destroyed by the digestive acids. Besides, Lionfish venom is also destroyed by the heat of cooking the fish.

Are lionfish dangerous to swimmers?

No, lionfish will move out of the way if a swimmer unwittinly comes close to them, and they will never attack. Lionfish are only dangerous when you mess with them.

Can I ask something else?

Absolutely, feel free to send in other questions by clicking here.