Just your garden-variety poisonous catfish

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Above, Northern Madtom (Noturus stigmosus), a venomous catfish species, collected from the Huron River near Ann Arbor, Michigan. New research suggests there are at least 1,250 and possibly more than 1,600 species of catfish that may be venomous and can inflict a painful sting. Catfish venom glands are found alongside sharp, bony spines on the edges of the dorsal and pectoral fins, and these spines can be locked into place when the catfish is threatened.

U. MICHIGAN (US)—Venomous catfish are far more common than previously thought, a new study finds.

The good news is that most use their venom as a self-defense mechanism against predatory fish and not in an aggressive way, says Jeremy Wright, a graduate student at the University of Michigan.

Wright’s research, which was published online Dec. 4 in the open access journal BMC Evolutionary Biology, says at least 1,250 and possibly more than 1,600 species of catfish may be venomous and can inflict a painful sting.

In other parts of the world, some catfish have extremely toxic venoms that can be deadly to humans.

Using  histological and toxicological techniques, as well as previous studies of evolutionary relationships among catfish species, Wright cataloged the presence of venom glands and investigated biological effects.

Catfish venom glands are found alongside sharp, bony spines on the edges of the dorsal and pectoral fins, and these spines can be locked into place when the catfish is threatened, Wright explains.

When a spine jabs a potential predator, the membrane surrounding the venom gland cells is torn, releasing venom into the wound.

In his paper, Wright describes how catfish venoms poison nerves and break down red blood cells, producing such effects as severe pain, reduced blood flow, muscle spasms, and respiratory distress.

However, because none of the species he examined produces more than three distinct toxins in its venom, each species probably displays only a subset of the whole repertoire of effects.

The main dangers to humans who tangle with North American catfish come not from the initial sting and inflammation, but from secondary bacterial and fungal infections that can be introduced through the puncture wound or when pieces of the spine and other tissue break off in the wound, Wright says.

“In such cases, complications associated with these infections and foreign bodies can last several months.”

On the evolutionary side, Wright’s analyses point to at least two independent origins of catfish venom glands. In addition, the toxic proteins show strong similarities with, and might be derived from, previously characterized toxins found in catfish skin secretions.

Surprisingly, those toxins in catfish skin secretions have actually been shown to accelerate wound healing in humans.

While it’s possible that the proteins from their venom glands could have similar properties, it’s probably not very likely, given the known effects of these venoms on humans, Wright says, although it may be worth further investigation.

“I’m currently working to isolate particular toxins and determine their chemical structures and the genes responsible for their production,” he says.

“It’s a very poorly-studied area, with little in the way of scientific literature to draw on, and my studies are just getting off the ground.

“So at this point it remains to be seen whether they’ll have any therapeutic value, though it’s worth pointing out that toxins from the venoms of other organisms—snakes, cone snails, and scorpions, for example—have all been put to pharmaceutical and therapeutic use.”

Further examination of the chemical composition of the venoms also will provide valuable insight into the mechanisms and potential selective factors driving venom evolution in fishes, Wright says.

Wright received financial support from the Museum of Zoology and the Rackham Graduate School, both at the University of Michigan.

University of Michigan news: www.umich.edu/news/

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8 Comments

  1. Cool Garden Things

    My uncle Pat got stung by one of these one time as we were fishing in brackish water down south…it was on the hook and my daughter was about to grab it-so he intervened and he got stung in the hand…when we finally got back to the house he had to go to the hospital…he says it was the single most painful experience of his life….
    GartenGrl at Planning Plants to Plant

  2. Benny13

    Nice to see someone who really knows their subject. Good work on this. Home Garden

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  4. glasshouse

    Some catfish have extremely toxic venoms that can be deadly to humans, these are found in all over the world. Thanks for the article writer who drawn a attention to some on good issue.

  5. T. Glick

    My son was jabbed in the webbed part of his hand between his thumb and index finger. It went so deep it was stuck. Holding the fish with his other hand, I cut the spine from the fish, then we were able to remove the spin from his hand. He immediately started to get purple lines running up from his wrist toward his elbow. I had him soak his hand in very hot soapy water which caused the purple lines to diminish. We continued to soak it every day 2-3 times. The swelling has gone way down after 6 days. But he also said this was pain that brought him to tears and he’s 25. Very painful. There had to be some type of poison in this catfish.

  6. aishah

    hello,
    it’s nice to know more aboutthe catfish. what are those chemical?????

  7. kiki

    I was stung by a catfish about 10 years ago down in Gulf Shores, AL. My cousin caught the fish off of my Grandfather’s dock and I was barefoot, unknowing of the potential risk. The catfish was flopping around on the deck and within the blink of an eye I saw it’s fin bone stab my foot and along with it came the most excruciating pain ever. Is this really considered to be comparable to a snake bite? If so, that’s something to brag about!

    It sure was painful and I broke out in severe tremors. My Grandfather called 911 and they seemed to be familiar with the situation. They told me to just soak my foot in a tub of hot water to get the poison out. Regardless, the side effects I had from the sting were pretty scary! There was a LOT of blood (imagine being literally ‘stabbed’ with a chopstick) and my entire body went into convulsions.

    I agree with this article. I think that this is something that needs to be researched much more for both preventative reasons and also for curative purposes as well.

    I have never broken a single bone in my body…but I’ve been struck by a catfish! Not many people can say that. Pretty cool! Although I don’t recommend it…..

  8. Dj

    I was fishin with my fsmily and girlfriend when I decided to show off by gettin the catfish off my dads wife hook and the fin went through my pinky and in my other finger and I noticed a red line goin up my arm towards my heart went to a local hospital and found out it had gave me blood poisin they gave me a shot inm my butt.but this issue does needs to be researched about.

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