Top 5 Most Poisonous and Venomous Fish!

By Dana Sackett

Many TV shows and nature guides have been dedicated to educating the public on the most poisonous and venomous spiders, snakes and even frogs, but what about fish? Unlike spiders or snakes, we rarely hear about which fish are the most poisonous (or venomous). This week we are dedicating our blog post to these hazardous fish.


First though let’s clarify some terminology. Poisonous and venomous are terms often used interchangeably but they have different meanings. A venomous animal has a means of injecting their toxin into another animal, whereas a poisonous animal can only deliver their toxin in a more passive manner (by being touched or eaten). A common example given to clarify this difference is that frogs are poisonous while snakes are venomous. It is also important to note that the affects from a venomous fish sting can often be relieved by immersing the wound in hot water (~105–115F) because these toxins are heat labile (meaning they can be destroyed or altered by heat).

1. Pufferfish (some species are also called toadfish) have been given the title ‘Most Poisonous Fish’ and have also been labeled the second most poisonous vertebrate in the world. The toxin responsible for ranking this fish so high in the “danger zone” is called tetrodotoxin. Tetrodotoxin is neurotoxic and inhibits neural transmission leading to weakness, paralysis, and even death at relatively low concentrations (~2mg). This toxin is found in the fish’s liver, ovaries, intestines and skin, leaving muscle tissue with relatively low and somewhat safe levels to eat. However, only highly trained and certified chefs are allowed to prepare this fish for consumption; a common practice in Japan where pufferfish are considered a delicacy.

A Valentin’s sharpnose puffer (Canthigaster valentini) photographed at Pure Aquariums in Lincoln, Nebraska. Photograph by Joel Sartore, National Geographic Photo Ark. Source

A blue-spotted puffer (Canthigaster solandri) photographed at Pure Aquariums in Lincoln, Nebraska. Photograph by Joel Sartore, National Geographic Photo Ark. Source

2. Stonefish have usurped the title of ‘Most Venomous Fish’ in recent years. They often resemble encrusted stones (hence the name), blending into their natural environment with ease. They deliver their venom through a row of spines on their back that can be extended when threatened (or stepped on). Venom is involuntarily expelled when pressure is placed on the fish and the more pressure the more venom. They reside in the Indo-Pacific region and northern Australia. A sting from one of these fish can cause excruciating pain, rapid swelling, tissue death, muscle weakness, temporary paralysis, and in very rare cases death.

A venomous reef stonefish camouflaged as a rock in the Indian Ocean. Source

3. Lionfish were thought to be the most venomous fish until recent years when stonefish stole the title. These conspicuous fish have venomous dorsal, anal, and pelvic spines covered by a loose sheath that moves down and compresses venom glands when the spine punctures tissue. A sting from these fish can cause extreme pain, swelling, and in very severe cases, cardiovascular collapse. Most lionfish naturally reside in the Indo-Pacific but they have become an invasive species in recent years; most notably along the Atlantic coast of the United States where they are having a major impact on Atlantic coral-reef communities. Lionfish were likely introduced along the Atlantic coast through aquarium releases.

Lionfish (Source)

4. Stingrays are one of the most common groups of fish responsible for human envenomations; largely because many rays bury themselves on the seafloor where people unintentionally step on them. Stingray venom is generally cardiotoxic. The Bluespotted (native to the Indo-Pacific) and Southern (native to the southeastern US) stingrays are some of the most venomous of all stingrays. As a form of warning others, the Bluespotted stingray generally displays its bright blue colored spots as a warning to predators of its highly venomous sting.

Bluespotted stingray (Source)

5. Boxfish and trunkfish are closely related to pufferfish. While these fish are not nearly as poisonous as puffers, they do have an impressive way of defending themselves with poison. When threatened or stressed, they excrete a toxin from specialized skin cells into the water, poisoning marine life in their vicinity. The Hawaiian boxfish in particular excretes a toxin called ostracitoxin or pahutoxin that is known to breakdown or destroy red blood cells.

Boxfish (Source)

Some other venomous fish to check out are other scorpionfish (besides the stonefish and lionfish mentioned above), stargazers, which have two venomous spines in addition to organs near their eyes that cause electric shocks, and striped eel catfish.

Stargazer (Source)

If you know of any other venomous or poisonous fish not mentioned here or have experience with a species listed here please share your knowledge and experience below.

Be sure to like The Fisheries Blog on Facebook and follow us on Twitter (@FisheriesBlog).


Auerbach PS. 2007. Marine envenomations. Adapted from the 5th edition of the textbook wilderness Medicine by Mosby-Elsevier.

Barss P. 1984. Wound necrosis caused by the venom of stingrays: pathological findings and surgical management. Med J Australia. 141: 854-855.

Boylan DB, Scheuer PJ. 1967. Pahutoxin: a fish poison. Science. 155:52-56.stingrays

Diaz JH. 2008. The evaluation, management, and prevention of stringray injuries in travelers.

Fenner PJ. 1998. Dangers in the Ocean: the traveler and marine envenomation. II. Marine Vertebrates. J Travel Med. 5:213-216.

Gwee MCE, Gopalakrishnakone P, Yuen R, Khoo HE, Low KSY. 1994. A review of stonefish venoms and toxins. Pharmacology and Therapeutics. 64:509-528.

Vetrano SJ, Lebowitz JB, Marcus S. 2002. Lionfish envenomation. The Journal of Emergency Medicine. 23:379-382.

Yang CC, Liao SC, Deng JF. 1996. Tetrodotoxin poisoning in Taiwan: an analysis of poison center data. Vet Hum Toxicol 38:282-286

47 Comments Add yours

  1. Jessica says:

    Great article! There are a few freshwater catfish species (the Madtoms) that have low levels of anti-predatory venom delivered via pectoral spines.

  2. In the Southern California waters I've had run-ins with Sculpin. Those guys have dorsal spines with venom. A friend of mine some how had one of those spines jab him under the big toe nail. Yeah, it hurt.
    We got him in the truck and drove up the 405 to UCLA Med Center. His toe was very swollen and multi-colored. He told me it felt like molten lead was injected under his nail. After several hours we took him home and bar-b-q'd that Sculpin fish and made really delicious tacos.

    1. Adrianne says:

      They’re actually scorpionfish… true sculpin are not venomous

  3. Stone fish and puff fish, they are most deadliest in my sense as most of the people die due to them. Japanese eat puff fish and they die due to food poisoning.

  4. Senena says:

    Yes in japan they do eat puffer fish but you have to be very careful when cooking it if you cook it right you’ll be fine but if you don’t the poison will still be in the fish they have professionals

  5. jual rpp says:

    I do agree with all the ideas you have offered on your post. They’re really convincing and will definitely work. Still, the posts are too brief for novices. May you please extend them a little from next time? Thanks for the post.

  6. Sam says:

    Excellent article you have here! Luckily, I have not had a poisonous fish encounter yet. Makes me more cautious on exploring areas I’m not familiar with. Thanks!

  7. Keenan says:

    It’s awesome designed for me tto have a site, which is helpful
    in support of my knowledge. thanks admin

  8. Maimona says:

    Are catfish poisonous

    1. Maimona says:

      Are catfish poisonous

      1. Vladimir says:

        See my comment below

  9. somnathbiseas says:

    Good .. am interested


    thanx for the post i never heard this this before keep up letting us know

    1. vids vidya says:

      I think that stargazer is a bit scary
      And poisonous

  11. Vladimir says:

    Striped eel catfish Plotosus lineatus have the venomous spikes in their fins. Incidental injection inflicted burning pain. The injured person can lose consciousness.

  12. Brad says:

    The flesh of the Greenland shark is toxic if eaten, unless it is left to be fermented. People in Iceland sometimes eat the fermented meat.

  13. barrygeller says:

    I have been in this hobby for almost 35 years in that time I have been stung jabbed and inadvertently impaled by all the above for me the worst was the catfish I thought it was dead but it was not going out without it having its way first. I reached in to remove it with my hands dumb really dumb. It thrashed and impaled it’s pectoral fin into my index finger. It does not pull out instead the poison is released slowly and the movr it moves the more is released. Got water and a trip to the er where my finger had to be cut open to remove it. Then left open so it would not burst. With every beat of my heart I wished I would stop. Never again wiki handle one of these not do I recommend it to anyone.

  14. Zach says:

    the wasspfish has really poisonous spines on its back and I feel that the longspine waspfish should’ve been on the list.

    1. Anonymous says:

      You are correct, waspfish are very venomous. They are another species in the group scorpionfish.

  15. Cheryl says:

    While this is a good compilation of information, and happy to see sources cited, a bit of credibility is lost with the choice of title. Of the 5 marine species listed, only 2 are poisonous. Even though you explain the difference, laymen reading this will remember the title and not necessarily the details, and thus perpetuate the use of ‘poisonous’ inappropriately to refer to the 3 that are venomous. Title selection is just as important as the text.

  16. Jim says:

    saya sudah melakukan tips poin 2 dan 3 untuk point 1 menyusul , Aerona

  17. Paul Larkins says:

    I would suggest you clarify the comments made regarding pufferfish. There are various species which, if one peruses the literature, have little or no presence of the toxins described in your article. According to what I have read so far, the Northern Pufferfish – Sphoeroides maculatus – has been consumed by many people along the Atlantic coast with NO reports of toxicity regardless of whether the fish is privately or commercially harvested and prepared. The incomplete presence of the facts can lead readers to stereotype groups of fish based upon what is stated instead of what is actual.

  18. BRAI BRAI says:

    my dad has been up close and personal with the PUFFERFISH YYAY!!!

  19. BRAI BRAI says:


  20. BeeKay says:

    I’d agree that the article, as fine as it is, needs to be more specific re. scope. If it is to cover the main venomous and poisonous fish, it should include the Box Jellyfish which does have a track record of fatalities and the Irukandji – not so deadly but causes serious injury.

    1. Anonymous says:

      You are correct that box jellyfish are very poisonous but they are not actually fish (despite their name). Maybe this blog could do a top ten most poisonous and venomous aquatic invertebrates.

  21. Emik says:

    Jeslly fish is one of the most poisonous fish

  22. shelia says:

    is aga eaters poison to to bass fish

  23. levi says:

    what about the blue ringed octopus

    1. brock says:

      hey do u like fishing what is your biggest fish you have caught

      1. brock says:

        why haven you replied yet

      2. brock says:

        hay $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

  24. Ali AlShekey says:

    Also there is Cone Shell , it knows as venomous and as predator.

  25. Suzie Snow says:

    We have Toadfish here in Md. We are on the East coast. They might be related to the Pufferfish.
    Also, we have the Snake fish everywhere now and they breed worse then roaches 10’s of thousands twice a year. They do have teeth and they can go days out of the water, they crawl on land. They prefer fresh water and eat other fish, insects, frogs ect;I personal think they would bite humans, but I don’t know. You tube has some video’s of them and they get big up to 3feet long. They I’ll eat fish devalue them like its nothing I saw one in captivity in an aquarium, the other fish was about half the size of him. They are fierce hunters, a predator to other aquatic, wild life.Thats all folks, lol 🙂 bye, bye Suzie Snow

  26. Necolas says:

    Great article you have there and quite educational too.
    There’s one thing i want to point out. It’s the picture you’ve used for Pufferfish (inflated). I think it’s not Pufferfish, I am pretty sure it’s Porcupine fish. Just want to add to that, it’s edible!

  27. Imani says:

    This is awesome

  28. Lancelot says:

    It was a belief here in Barbados when I was growing up in the 60s that if you got stung by a Stone fish which we called a lion fish although they say Lion fish only been around a decade or so ,(and are causing havock on our reefs so we eat them now ) that you had to get an antidote , now from here I am learning that you just threat with heat , and maybe some pain killers .

    1. Lancelot says:

      seems they been around a few decades since the 80s .

  29. ADUNJO SOLOMON says:

    The poisionois fish, is it eatable?

  30. Eduardo says:

    I live in PR and the last two times I have been snorkeling I have found three stonefish. They are not pretty fish and did not see to be intimidated. In our Island we have the longish as an invasive species, but fortunately I have seen any yet when snorkeling, probably because they are being captured to be eaten by people.

  31. Eduardo says:

    I live in PR and the last two times I have been snorkeling I have found three stonefish. They are not pretty fish and did not see to be intimidated. In our Island we have the lionfish as an invasive species, but fortunately I have not seen any yet when snorkeling, probably because they are being captured to be eaten by people.

  32. Matt says:

    I’ve seen the result of a stonefish sting, was not a pleasant sight!

  33. Sammy says:

    The two pics of the stone fish are not stone fish, but scorpion fish. And as somebody else wrote, the puffer fish pic is a porcupine fish.

  34. nice work, even if some picture’s name is not right.
    New Form of Nanorobots To Clear Blood of Toxins

  35. Alex says:

    The bullhead catfish it is a freshwater fish and it has venomous spines on both of the pectoral fins and the dorsal fin. The venom is very mild it might feel like a bee sting for a couple of days unless you are allergic of course.

  36. sexy says:

    my bro died from bofish

  37. WealthyPeeps says:

    loved reading your article. it was really informational for me. wish to see more in the coming days.

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