In their native Indo-Pacific range, lionfish (Pterois species) have a handful of natural predators that keep their populations in check, though they’re not exactly a top menu item thanks to those venomous spines. Outside that range—like in the Atlantic and Caribbean—predators are scarce, which is why they’ve become such a problem.
In their home waters, large groupers, particularly species like the Nassau grouper (Epinephelus striatus), are known to prey on lionfish. These hefty fish, which can grow over 4 feet and weigh up to 55 pounds, have the size and jaw power to handle the spines, either by swallowing lionfish whole or crushing them. Sharks, too, get in on the action—coral reef sharks (Triaenodon obesus) and tiger sharks (Galeocerdo cuvier) have been observed eating lionfish in places like the Red Sea and Pacific reefs. Moray eels, with their serpentine bodies and fearless attitude, are another contender; species like the giant moray (Gymnothorax javanicus) can maneuver around the spines and take lionfish down in tight reef spaces. Even the occasional snapper or barracuda might nab a juvenile lionfish if it’s small enough to avoid the worst of the venom.
The catch? These predators don’t specialize in lionfish. They’ll eat them opportunistically, but the venom—neurotoxic proteins delivered through those 18 or so spines—deters most from making them a regular meal. A 2018 study in Marine Ecology Progress Series found lionfish made up less than 5% of grouper diets in the Indo-Pacific, even where both were abundant. The spines don’t just sting; they signal “high-risk snack” to anything with a brain. Plus, lionfish are ambush predators themselves, often hiding in crevices where bigger fish struggle to reach them.
In invaded regions like the Atlantic, it’s a different story—almost no natural predators step up. Native groupers, like the black grouper (Mycteroperca bonaci), could theoretically eat them, but they don’t. Why? They didn’t evolve with lionfish, so they lack the instinct or tolerance for the venom. A 2021 experiment off Florida showed captive groupers avoiding lionfish unless starved and given no other options. Sharks fare better—nurse sharks (Ginglymostoma cirratum) and reef sharks have been spotted munching lionfish in rare cases, especially when speared or injured by humans first. But wild predation is negligible; a NOAA report from 2023 estimated less than 1% of lionfish mortality in the Gulf comes from natural predators.
Humans have tried playing matchmaker. In places like Belize, divers train sharks and groupers to eat lionfish by feeding them speared ones, hoping to spark a learned behavior. But scaling that up is a pipe dream; you’d need thousands of trained predators, and lionfish breed too fast (30,000 eggs every few days) to lose the numbers game. Also, it’s been debunked that they learn on their own and associate divers with food. It is now hazardous as the sharks and eels follow every diver expecting food. Divers have been bitten and harassed.
Other ideas float around—like the cornetfish (Fistularia commersonii), a long, skinny reef dweller that’s been seen eating lionfish in the Pacific. It’s got a tubular mouth that might dodge the spines, but there’s no hard data on it tackling them in invaded waters. Octopuses could theoretically do it too, using their smarts and beak to disarm the spines, but evidence is anecdotal at best.
Bottom line: in the Indo-Pacific, groupers, sharks, and eels keep lionfish from overrunning the place. In the Atlantic, nothing does—yet. Predators exist, but they’re not wired for the job.
Grab your ZooKeeper gear and get out and slay! Eat them to beat them! #SlayEatRepeat
