Well to avoid Ciguatera poisoning, the first step I guess is don’t eat fish, but that is a bit drastic, so the first takeaway lesson is be careful what you fish eat. That means if you are catching or eating fish then restrict your consumption to smaller species of the various pelagic ones and also of tropical reef fish. I know some cruisers who only stick to 5 kg (12 lbs) or smaller, preferably almost pan sized at about 1-2 kgs is best. I also know people who eat a small sample of fish almost as soon as it’s in the cockpit and if they get a bit sick then they throw the remainder. Not a great strategy acting as a guinea pig but whatever works.
Also restrain yourself from eating big portions of the any specific fish if there is a risk. Always ask the local fishermen where ever you are about the risks. I read somewhere that some people divide the fish up and place in marked plastic bags in the freezer so if one makes them sick or off color they know all of it is suspect. If you have a cat on board and you don’t really have a strong emotional bond or attachment you can emulate old sailors and give the cat some first.
Rule 1 - Don’t eat reef predators, especially the larger specimens. Of the 400 species that are susceptible the main fish species include the Surgeon Fish, Coral Trout, Coral Cod, Red Snapper, Spanish Mackerel, Queen Fish, Red Emperor, Sweet Lip, Trevally, Yellowtail Kingfish, Wrasse, Red Bass, Barracuda and Grouper. Large fish equals higher risk. Check out which species is the one to watch wherever you are. Talk to the locals.
Rule 2 – Don’t catch fish in any area that has been subject to reef disturbances such as storms and major weather events. Areas with dead coral or coral bleaching are suspect.
Rule 3 – Don’t eat the fish head, the roe (eggs), liver or any other viscera as this is where the toxins accumulate the most. Be aware that cooking does not destroy the ciguatoxins and the toxins are also unaffected by your gastric acids.
Rule 4 – There is no current rapid, economic or accurate method for testing ciguatera contamination in fish. The old sailor’s trick of feeding a sample to your ships cat may mean you need to carry a lot of cats and end up losing your best mate. I have heard that locals in some places use or allow flies and ants on the fish as an indicator, if they avoid means it is no good, however this is a highly unreliable methodology for testing, but that’s just me.
Rule 5 – Don’t eat fish that are much over 5 lbs (2 kgs) and smaller is better. Be careful what you eat as you are what you eat, very profound end I think.
One detection method I have been told of by a charter skipper I met called Gail, is that you should rub the fish liver on the lip and tongue, as this is where toxins accumulate the most. If the lip goes numb or tingling, the fish is suspect. It does work so don't be squeamish she assured me. A clever chap advised me that the common fish liver to the lips detection test, the only one many of us know, may only indicate fish with high levels of toxin so therefore not a foolproof and reliable test. He pointed out that low toxin levels also can cause illness, and toxin accumulation. The toxin is a fat soluble compound that takes a week or more to flush out of the body. Evidently there are cases where a pound a day of fish of low level toxin can cause quite serious poisoning by weeks end as accumulation rises to a significant level. The point made is that for safety the use of fish liver sampling is inherently flawed and is not 100% reliable and this we all understand. Other debunked folklore include besides the ant an fly test, is the turtle test, or that a thin slice of fish does not have a rainbow color when held up to the sun, or that a silver spoon will tarnish when exposed to infected fish in the pot.
There was a test kit, known as the Cigua-Check Fish Poison Test Kit which was developed by Dr Yoshitsugi Hokami of University of Hawaii School of Medicine. The kit has a verified sensitivity for Ciguatoxin of over 92% and a test result within 50 minutes. This kit was the only one to verify toxin in fish flesh, and was available worldwide. The bad news is that I am informed it is no longer available. So very hard to get a test without a path lab nearby.
Just as a caveat on the symptoms experienced with Ciguatera poisoning. There is a thing called Scombroid fish poisoning. This is caused by a toxin that forms when fish start bacterially decaying, and its often caused by improper refrigeration. The symptoms cam resemble Ciguatera poisoning and if your boat frig isn’t not keeping down to temperature and you get sick then also look at this. The onset of symptoms is quite rapid after ingesting infected fish. The common symptoms include all your old favorites such as nausea and vomiting, dizziness and outbreaks of hives and so on. The toxin behind this condition is known as the histamine “Saurine” and is usually found in Albacore Tuna, Yellowfin Tuna, Bluefish, Sardines, Herring, Marlin, Amberjack, and Abalone. Mahi Mahi (Dolphin Fish), Bluefin, Bonito, Mackerel and Skipjack all have relatively high amounts of Histidine. If the fish is poorly refrigerated or preserved the bacteria coverts the Histidine to Histamine leading to Scombroid poisoning. Often the fish tastes fresh and sometimes the contaminated fish has a peppery or spicy taste. It is said that toxins can form even after a temporary storage at too high a temperature. So be wary at fish markets, in many places nothing is iced, also process your own fish quickly.
Wait! There’s more! If you eat puffer fish, like some of those in Asia do, then symptoms can be somewhat similar. This is known as Tetraodon poisoning, and the bad news is its fatal in about 50% of cases. Also it must be noted that if you have been consuming shellfish and get sick then this may be due to Neurotoxic Shellfish Poisoning.
Good question. If you are local to hospital then having your stomach contents all pumped out is a good start. I have read that you should induce vomiting by taking Syrup of Ipecac, but somewhere else I have read that you should not do this. Well in most cases when away sailing you will not have either options so induce vomiting with the tried and tested finger down the throat method. If the person suffering Ciguatera poisoning is experiencing severe and persistent vomiting and diarrhea, then dehydration becomes an issue. Not everyone has access to a saline drip so you should use whatever electrolyte you can even if it means coming back up a lot. You may have to make a decision to seek urgent medical help if the person deteriorate. Also be aware that consumption of alcohol, more fish and shellfish, nuts and nut oils can possibly trigger recurrent Ciguatera poisoning symptoms.
I have read a French scientific paper, that undertook research in New Caledonia and Vanuatu, and looked at the efficacy of traditional island methods for alleviating the effects of ciguatera poisoning. Some are a bit hard such as swallowing 3-4 fresh chillies. Another involves boiling unripe paw paw and drinking the water and eating the boiled paw paw. There are literally dozens of concoctions involving boiling leaves of various plants and so on. This paper had looked at 64 different plant species that reputedly are effective in treating ciguatera, and these folk remedies were either preventive or curative. The paper concluded that listed preventive methods were questionable as the toxin is known to water insoluble and heat resistant. There were many plants that were part of popular treatments in both Melanesia and Polynesia and too detailed to list. The remedies were primarily single plant species. A number of species were well known for their anti-diarrheal and ant-dysenteric and antispasmodic intestinal effects. Interesting paper indeed. All about ciguatera poisoning and how to cook seafood.