Ciguatera poisoning is caused by ciquatoxin, produced by reef plankton. Some fish that directly eat the plankton, kole and palani for example, build up dangerous levels of the toxin, and all reef predators that eat the fish that eat the plankton accumulate the toxin. Human consumers of tainted fish gradually accumulate enough of the toxin to the point it affects them. One fish with very high levels of ciquatera, or a slightly tainted fish that pushes the human consumer over the edge, can bring on a very bad experience.
It is believed that the ciguatoxin levels on the reef fluctuate seasonally, and thus, the species that have a reputation to be “hot” may or may not have dangerously high levels depending on whether a bloom is going on. Since most predator fish, like papio/ulua, kaku, etc, travel anyway, it’s not wise to think fish from one particular area is “safe”.
A few scientific studies have been conducted in the past decades. This one, by the Hawaii State Dept of Health, grouped species in fairly broad categories, indicating how many of the 736 implicated fish were of a broad species. “Jack Fish” caused the highest number of poisonings, and is comprised of papio, ulua and kahala. Surgeonfish (kole, palani, kala) is next, grouper (roi, hapuupuu), and snapper (wahanui, taape, uku, toau) follow. What’s not clear is the percentage of each species group consumed that didn’t cause a reaction.
In another publication, the Hawaii Seafood Council refers to a study conducted between 1999 and 2003, listing the top 10 fish species involved in ciquatera poisoning. Interestingly, uku (#7) is higher up in the list than wahanui (#9), yet you no longer hear of uku being “hot”. However, the web is full of references of how “hot” wahanui is.
In yet another survey, published by the Hawaii Dept of Aquatic Resources, divers speared roi in West Hawaii (Big Island) and Oahu, and autopsied them to determine ciguatera level. All the roi tested positive for ciguatera, with 25% of the West Hawaii ones and 8% of the Oahu ones at levels unsafe to consume.
Traditionally, big papio, ulua, kahala, kaku, wahanui and kole have been likely ciguatera suspects before roi were introduced to Hawaii. Even uku to some degree, but possibly less because uku feed at mid depths when they get bigger. So what does this all mean in regards to how safe your fish is to eat? To minimize risk, don’t consume large individuals of these species, and limit your reef predator consumption in general.
Interesting stuff, Scott! Goes to show that anecdotal evidence should always be taken with a grain of salt. I find it interesting, for instance, that Kaku make up a relatively small proportion of all reported incidents, yet that’s one of the species you hear about the most when the subject of cig comes up. I don’t eat a lot of reef fish these days (I had more than my fill growing up) but I’m glad my two favorites, aholehole and aweoweo didn’t make the list!
Great article. Lots of good info. That study on the top 10 fish species is a little confusing. If the ranking is based on reported cases, it may not be taking into account how often certain species are being eaten. Kaku and kahala not being on the list could mean people avoid eating them because they’re known to have ciguatera – not because they are less “hot.”
Hi Jason,
I was thinking the same thing. Kaku didn’t even make the top 10 in the 1999 to 2003 survey. A lot of cig cases go unreported though. Maybe kaku isn’t eaten as often as the other fish, and maybe those that got sick eating kaku didn’t report it? Who knows.
Oio is safe though, if you decide to eat one you catch. 🙂
-scott
Yes, that’s true, it is somewhat of a flawed of study. You’d really need to look at number of incidents per species compared against the total number of individuals eating that species, although this would be nearly impossible, at least as an observational study.
Detecting Ciguatera
In Northern Australia, where ciguatera is a common problem, two different folk science methods are widely believed to detect whether fish harbor significant ciguatoxin. The first method is that flies are supposed not to land on contaminated fish. The second is that cats will either refuse to eat or vomit/display symptoms after eating contaminated fish. A third, less common testing method involves putting a silver coin under the scales of the suspect fish. If the coin turns black, according to the theory, it is contaminated.
On Grand Cayman and other islands the locals will test barracuda by placing a piece of the fish on the ground and allowing ants to crawl on it. If the ants do not avoid the flesh and will eat it, then the fish is deemed safe.
Hi Mike,
Thanks for sharing the folk science methods employed Down Under. Are any of the methods pretty reliable?
Mahalo,
scott
I was hoping someone could confirm any of these. So far, the fly trick seems to work. I leave a questionable fish cut up outside and watch it to see if any flies land on it to nibble. Haven’t gotten sick yet but not 100% if this is reliable.
Cig poisonings haven’t been reported lately in Hawaii. Not sure if there are less cases or they just aren’t being reported. I do think people are staying away from the riskiest fish like the large predators that prey on reef fish.
Uku (gray snapper/jobfish) were implicated in the past but I haven’t heard of any uku related cases personally. And uku is sold in fish markets and served in restaurants. Big ulua (GT) and kahala (amberjack) are still considered suspect.
Do any the offshore species have any level of risk? I’m wondering about tuna and mahi mostly, but I’m kind of curious about bottom fish too.
Hi Kawika,
It is my uneducated opinion that offshore species could have a trace amount of cig due to eating fish that may have consumed traces of the cig, but the amount of cig in those offshore species is very low.
The deep bottom fish have very low levels of cig also unless they fed on reef fish when they were young and shallower dwelling. Species caught bottom fishing that have been implicated in cig poisoning are hapuupuu, uku, kahala, papio/ulua.
I would think it’s safe to eat tuna and mahi.
thanks,
scott
I got Ciguatera poisoning in 1990 from imported frozen ‘Mahi Mahi’. However it was imported from Taiwan and could have been any whitefish. I was initially misdiagnosed and had severe neurological symptoms for years, temperature reversal of hands and feet, sleep paralysis with hallucinations, extreme weakness of my extremities.I was disabled for the first year. I have what’s known as chronic ciguatera poisoning. I still have symptoms after doing activities that cause intense fat burning. We call it Cigging when I’m symptomatic. I’m very careful about what fish I eat and mostly stick to Ahi, Ono and other safe Hawaii fish., and Alaska wild Salmon. There have been reported cases of salmon in Washington state having it when they returned to fresh water to spawn.
Hi Julie,
Very sorry to hear of your ongoing ciquatera poisoning symptoms. I’ve heard that the ciguatera has to build up to a certain level to show outward symptoms, and is rarely seen in people that haven’t eaten a lot of fish with cig toxicity. Is it possible you did build up your level of ciguatera before eating the poisoned mahi mahi?
There are other food poisoning incidents caused by other toxins in fish but I don’t know if those are cumulative like cig is.
thank you,
scott
In 1995 While I was working as a bio-science tech on Kure Atoll, NWHI, I caught and eat a large mullet, I dined on the belly of the Mullet, my two partners eat the fleshy part of the mullet, it wasn’t long before I developed symptoms, it lasted about 48hrs, hot cold sensations, vomiting, dizziness it was a rough time, my two partners on the other-hand had no symptoms. A couple years later a neighbor in Ewa Beach caught a jackknife while diving on Molokai, he spent over a month st Queens Hospital suffering from cig, it nearly killed him.
Hi Kamuela,
Wow, those two incidents speak to the “one very hot fish pushing over the ciguatoxin tolerance level”. Have you or your neighbor had any symptoms eating reef fish after those incidents?
We don’t hear of folks getting sick from cig anymore. You think it’s just under reported or there’s less cig in our fish now/
thanks,
scott
Hi Scott, regarding your question, I’m not sure about my former neighbor, but I can tell you I have not had a MAJOR cig related symptoms since, I love my reef fish, the experience hasn’t stopped me from eating Kole, Manini, or Roi, Note; I’ve always enjoyed eating Roi…though since my experience years ago, I now remove the head and the belly area’s, I dine on the fleshy parts. About six months ago a friend bagged about a dozen large Uku’s on Penguin Banks, blessed me with one, I prepared-it, and the family and I dined on it, a short time after I experienced a numbing sensation in my mouth and tingling in my hands….but that was it?…..no one else experienced any related symptoms, needless to say I was stressing for a few hours thinking the worse was yet to come. Do you know anyone that has been exposed to cig eating Mu?
This is really good info, thanks! So for you, it’s not true that you hit the max your body can take and now any cig you’re exposed to causes you to react.
Not sure what your reaction was to the uku but that concerns me since I target uku and give to friends. Maybe the tingling sensation was due to slight spoilage or something less toxic than cig?
And I haven’t heard of much Mu – Cig cases. Mu eat a lot of shellfish, and I don’t know if those shellfish built up any cig.
Hi Scott, (In regards to Under Reporting or Less Cig)
I don’t really know how the data is collected or how it’s verified, I do have friends that have had it, got treated for it, and or whether the data was harvested by someone is unknown to me. Personally I think it’s a seasonal type of exposure, mores during the warmer months then the cooler months…Just my opinion.
Appreciate all the info you’ve shared, since we hear so little about cig now. I’m very worried I’d poison someone with fish I’ve given them.
If its reef-fish I usually sample a couple before giving the rest away….So far I’ve had no issues. In regards to the Uku, thats always a possibility, the fish may have been sick, or carrying something other than cig.
Once, years ago when I was working on the mainland, our boss brought mussel poke back from Tamashiro Market and da boys and I grinded some at work.
Within 30 mins I was puking in my waste basket but no one else had any issues. To this day I can’t eat mussel poke. Maybe I had a bad mussel or maybe I had
some stomach virus?