17 Most Deadly Fish of the Pacific Ocean

Ocean dwellers come in different creepy shapes and sizes, and some of them are actually warning signs for you to keep off. From the more common sharks to sting rays and flower urchins, these 17 Pacific natives can cause you a lot of trouble and pain.

Box Jellyfish

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A sting from the box jellyfish’s very slender, poisonous tentacles (nematocysts) doesn’t take long to get you in a bad spot. In only a few minutes after being stung, people and other animals face paralysis, cardiac arrest, and death. Thankfully, not all stings are fatal.

Reef Stonefish

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The reef stonefish is dangerous—so dangerous that it holds a place as the most venomous fish in the world. This creature found in the Indo-Pacific Ocean has poisonous dorsal fins lined across its spine, and just a misstep from you causes intense pain and, sometimes, death. Its camouflaged, stony look doesn’t help matters if you’re trying to avoid it.

Puffer Fish

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With pufferfish, you’re in danger only if you love unusual, exotic seafood. The National Geographic reports that one pufferfish has enough poison to kill 30 adult humans. Their tetrodotoxin is over 1000 times more lethal than cyanide, and they’re also foul-tasting, to say the least.

Moray Eel

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The moray eel, found in the south-east and south-west parts of the Pacific Ocean, may not kill you, but it can cause you to lose a limb. It holds a massive bite force of 300 to 700 PSI. For comparison, your dogs, known to have “powerful bites,” only exert an average of 235 PSI.

Box Fish

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You’d want to be particularly wary about the yellow box fish. Found in the eastern parts of the Pacific, the box fish has a rather peculiar method of self-defense. It attacks its red blood cells at the gills with Pahutoxin, causing a failure of breath to their predator when bitten. They aren’t as deadly to humans as their pufferfish family, though.


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The danger with the stingrays isn’t from toxic venoms but from the puncture wounds their tails can cause. Although death from them is rare, a sting into your heart, abdomen, or other vital organs can prove fatal. CNBC reports that popular crocodile hunter and TV host Steve Irwin lost his life to a short-tail stingray barb that punctured his chest.


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Merely looking at the barracuda, you know just what type of danger it poses. These lightning-fast fish with eerie-looking teeth don’t prey on humans or kill humans as often as sharks. Nonetheless, there are reports of human deaths by them, usually provoked during spearfishing.

Pacific Electric Rays

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It’s an electrifying experience when you come into contact with these flat natives of the northeastern Pacific. They emit up to 45 volts—enough to knock down grown adults—and will even approach you when they feel threatened. There may not be recorded fatalities from them, but divers are generally warned to stay away.

Bull sharks

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According to National Geographic, bull sharks are the most dangerous sharks in the world. Although they don’t kill as many people as great whites, human encounters are quite common. Bull sharks have a reputation for aggressively hunting in human-populated waters along tropical shorelines.


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In the same family as the stonefish but not as deadly, the lionfish also comes with extremely poisonous dorsal fins you don’t want to mess with. A sting from this fish will cause you intense pain, nausea, abnormal changes in heart rate, convulsions, and fainting.


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The fugu uses the same deadly toxin as the pufferfish to defend itself from predators—tetrodotoxin, known to be 1000 times more lethal than cyanide. Getting this into your bloodstream can cause paralysis, difficulty breathing, and even death. Ignoring this, like pufferfish, they feature as delicacies in exotic restaurants (with licensed chefs) across the US.

Flower Urchins

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These Indo-Pacific urchins hold a significantly dangerous amount of venom in cup-like flowers spread all around their body. Their stings are extremely painful and can cause respiratory issues and paralysis. They’re also the most dangerous urchins and a very common sight in the ocean.

Great White Sharks

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The Guardian reports that there were ten fatal shark attacks in 2023, and great white sharks posed the most threat. A single “test bite” from them is enough to make anyone bleed to death. You’ll find these dangerous killing machines across the US Pacific—from Alaska to California and Hawaii.

Oceanic White-Tip Sharks

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Another group of lethal sharks are the oceanic white-tip sharks, a hefty-bodied species with subtle white markings on all their fins. As the University of Florida shares, “they are known to have attacked survivors of ship and plane wrecks at sea and are suspected to be responsible for several unrecorded human fatalities.”

Crown-of-Thorns Starfish

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They’re the most dangerous starfish on the planet, and their eerie-looking coat of thorns does more than just puncture your skin. Crown-of-thorns starfish also have neurotoxins on their spines that cause nausea and painful swellings that can last for over a week.

Giant Trevally

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The giant trevally isn’t a particularly dangerous species that will poison you or eat you up like a shark. Instead, the danger from them is particularly reserved for your limbs. You’re advised not to feed these Indo-Pacific dwellers, whether they’re alone or in a group, as they can bite off your finger, mistaking it for food.


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Triggerfish is one of the least dangerous fish on our list, but it’s best to avoid it nonetheless. They have teeth designed to be able to crush corals, so you understand how bites from them can be extremely powerful and painful to bear. Females at nests can get quite aggressive too.

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