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How To Avoid And Treat Fish Poisoning (Seafarers’ Pain)


One of the more popular pastimes for many seafarers is fishing. It seems no sooner has the anchor grabbed the bottom, then the lines and hooks are thrown over the side and the angling begins. However, it seems that sometimes there are serious safety concerns to consider hence, if you like to fish you have to know how to treat fish poisoning.

Fish poisoning on board

There have been numerous instances in the past couple of months of seafarers being made ill by fish caught off the ship and then cooked onboard. Some crew have been seriously poisoned and there have even been a couple of deaths.

According to food experts, eating fish caught off the side of the ship is a sure way for the crew to contract food poisoning.

One of the most common types of problems from fish caught this way is “ciguatera” poisoning. This is caused by eating tropical fish that consumed toxin-producing algae.

Stomach bacteria

Want to treat fish poisoning? There is no effective treatment or antidote for ciguatera poisoning. The mainstay of treatment is supportive care.

The fact is that while waters may look clean and while fish caught may look fine – there are so many hidden dangers. It is impossible to tell if the fish has been swimming in “red tides”, and has been consuming toxic algae, and there are a whole host of other toxins which may be in their systems.

Plus, and how to put this delicately, where one ship anchors usually many have…and – well, even treated sewage is not the most appealing of diets for your dinner to have chomped down on…and so that is something to consider too.

How fish becomes poisoned with “ciguatoxin”

Big fish eats small fish

‘Natural selection’ is the differential survival and reproduction of individuals, a key mechanism of evolution. The term was popularised by Charles Darwin.

Only fish in warm waters become hosts to a poison called “ciguatoxin”. It all starts on tropical reefs, where ciguatoxin-bearing micro-organisms make their way into the food chain. Tiny reef fish ingest the toxin, they then get eaten by larger fish and so it goes on…until some unsuspecting Third Mate has his dinner and nearly dies.

Thankfully, not all tropical and subtropical saltwater fish get it. It depends on what type of fish they are, what they feed on – and where they feed. Fish are incapable of ridding themselves of the toxin, once it’s in it stays with them – and although it causes the fish no harm at all, it accumulates in their flesh.

So the bigger and older the fish, the more likely they are to carry the most ciguatoxin and represent the greatest danger. How can we spot if a fish is carrying ciguatoxin you may sensibly ask. The answer is, you can’t. A fish with the toxin looks the same, smells the same and even tastes the same as one without it.

You may be forgiven for thinking that only vessels in the tropics would be affected – after all that is where the poisonous fish are. Well, rather cunningly some cooks freeze the fish – and so when they are cooked weeks later, then all the crew become ill. If fish have been caught from the ship there is a real chance of being struck ill however long before they are actually consumed.

Food poisoning symptoms

Man with his head in a toilet.

An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness.

You really do not want to experience ciguatera fish poisoning. The illness is characterised by a combination of gastrointestinal and neurological symptoms. So it gets you all ends up and in the middle…and it can hit you hard.

There is no real need to ask how you will know if you have ciguatera poisoning – because like falling in love…boy you will know. Even a mild dose of ciguatera poisoning will leave you feeling distinctly unwell. Symptoms will usually arrive within 3 to 5 hours of eating the fish and might include:

  • stomach ache
  • head ache
  • dizziness
  • vomiting
  • diarrhoea
  • general numbness
  • a tingly sensation of your arms and legs, and around your mouth

For a severe dose, expect all of the above, plus some delightful and surprising additions:

  • muscle pain
  • tooth ache
  • blurred vision
  • hair loss
  • loss of nails

Owing to the total mess it makes of your nervous system, cold things will feel hot and vice versa. In the most severe cases, this may be followed with muscle paralysis, coma and eventual death through respiratory paralysis. If you survive, recovery can take months and some symptoms may linger for years.

How to spot poisoned fish

dead fish in toxic water

National Geographic statistics indicate that on average 8 million tons of plastic trash dumped in oceans a year.

Unfortunately there is no way of spotting a toxin laden fish from a healthy one. As with anything maritime related there is much local folklore about simple tests for the toxin.

Some say to ‘lay a silver coin on the fish and see if it goes black’, or to ‘cook sweet potato with it and see if it changes colour’. Another bit of ‘advice’ is that you should leave a piece of fish out in the open. If the flies won’t settle on it, it’s got ciguatera.

No if you have ever seen the things that flies are willing to settle on, it may be better to treat this with a degree of scepticism!

In fact, none of these fishy wives tales have any basis in science and are downright dangerous if treated with anything but total disdain. The fact is you can’t tell, and if any fish are caught then it becomes a game of Russian roulette, with potentially diarrhoea consequences.

How to avoid or treat food poisoning

Dead, poisoned fish with guts outside

If want to minimize a risk of being poisoned then never eat: liver, gills and guts or any internal organs.

What can you do to fight the poisoning if it strikes? ‘Not much’ is the unfortunate answer. You can try to reduce the symptoms – drink plenty of water, induce vomiting to rid the body of as much of the toxin as you can. But it is vital to seek qualified, professional advice immediately symptoms of ciguatera poisoning occur.

The key then is avoiding getting ciguatera poisoning in the first place. So what can you do to minimise the risk – well the obvious answer is ‘don’t eat fish’ – but if you must, don’t eat fish caught near reefs or in tropical waters.

If you can’t fight the temptation of feeding on fishes, there are several parts you should never eat. They are:

  • the liver
  • the gills
  • the guts or any other internal organ

Remember that neither cooking the fish nor deep freezing it will affect the toxicity of a fish carrying the poison. Please remember, ciguatera poisoning is dangerous – take chances with fish caught of the ship at your peril.

(Captions are taken from Wikipedia online resource)