Since I’ve been the bearer of warnings about fish and various unpleasant consequences, I figured I may as well finish the job. After all, forewarned is forearmed. While my previous cautionary tales were about improperly labelled fish and potential tummy troubles, these deal with food safety issues alone – issues you might want to be aware of if you’re heading to hotter climes during the winter. A little knowledge might save you from ruined vacation days and might also help you to figure out the source of your problems should you become ill.
While they’re more common in tropical locales, here are a few potential culprits that can strike at home base too:
• Large tropical reef fish
In the tropics, small fish love to eat the algae found in coral reefs. But there is a toxin that lurks there as well: ciguatera. Consumed in minute amounts, there is no problem. But as we all know, big fish like to eat small ones; over time, in large reef fish such as barracuda, grouper, different varieties of snapper (not yellowtail snapper) and king mackerel, the amounts of the toxin can build up. It doesn’t affect the taste or appearance of the fish in any way.
Symptoms of ciguatera poisoning can include gastrointestinal problems (nausea, vomiting and diarrhea) and neurological ones such as tingling fingers or toes or finding that cold things feel hot and hot things feel cold. In addition, some people do suffer cardiovascular symptoms such as arrhythmias. At one time, it was thought that there was a cure – the administration of a sugar alcohol called mannitol – but studies have thrown out that theory, so at this point there is no antidote. It’s thought that a treatment – activated charcoal – may help to minimize symptoms but it only works if used within three to four hours after ingesting the toxin. Generally if someone has ciguatera poisoning, you simply have to treat the symptoms (antihistamines, cool showers etc.) until they disappear but some may last for days or months
So if you’re heading to Florida, the Caribbean or Hawaii, the best advice when it comes to eating these fish is to avoid eating the head, roe and liver of warm water ocean fish, as the ciguatera toxin is most concentrated in these parts. In addition, go for smaller fish- those that weight less than six kilograms per fish. If you’re unsure when buying fillets of fish, go for other options.
When not properly chilled, scombroid fish, which includes fresh and frozen tuna, mackerel, mahi mahi and escolar, can lead to high levels of a substance called histamine. This is the same compound involved in allergic reactions, but scombroid poisoning can happen to anyone, not just those with allergies. It can cause symptoms that include facial flushing, rash, hives, sweating, tingling or burning sensations of the mouth and throat, dizziness, nausea, headache, abdominal cramps and short-term diarrhea. In serious cases, it can also cause respiratory distress and swelling of the tongue, severe enough to require hospitalization.
Most cases, however, tend to be of the mild variety. But if you suspect scombroid poisoning, contact the eatery or supplier to let them know so that they can change their handling practices. Sometimes scombroid poisoning can be difficult to pinpoint as you can have one or two of the symptoms, but if it happens more than once from the same source, consider reporting the case to local public health officials and also avoiding the establishment.
For those of you who avoid fish and seafood due to allergies, there’s something quite surprising that you might want to steer clear of as well: beer. Isinglass, one of the dozens of compounds that can be used in beer making, is a substance derived from dried fish. If you have an allergy and have ever suffered a reaction after drinking beer, that could be why.
In Canada, even with our new comprehensive allergy labelling laws, standardized beer does not have to put this on the label. The beer industry fought long and hard to be exempted.
But before you swear off fish, keep in mind that there are plenty of other fish in the sea that are safe and offer an array of health-promoting advantages.