Ichthyoallyeinotoxism: Hallucinogenic Fish

When you go out to eat, there's always the potential for concern about contaminants. Worried about salmonella? Trichinosis? How about hallucinating:

Two men have suffered terrifying visual and auditory hallucinations after eating a popular local seafish in Mediterranean restaurants.

According to a clinical study on the patients, which is due to be published in the journal Clinical Toxicology, the men started seeing and hearing things after contracting a rare form of hallucinogenic poisoning from the Salema fish they were dining on.

The species is a popular food fish and is not normally hallucinogenic...

...Indoles, with similar chemical effects to LSD (lysergic acid diethylamide) are believed to be responsible and may be consumed when the fish eat algae or phytoplankton containing the chemicals. All of the species effected by ichthyoallyeinotoxism are algal grazers.

Others have claimed that different species of ichthyoallyeinotoxic fishes, such as Kyphosus fuseus, contain much more potent hallucinogens, such as dimethyltryptamine or DMT, which is considered to be one of the world's most mind-bending hallucinogenic chemicals.

(note for link to Clinical Toxicology article: get the pdf. The HTML version is almost non-readable.)

I can't comment on the previous cases they refer to, but in the two case studies covered in the Clinical Toxicology article, the experience sounds much more like the literature description of the effects of a tropane alkaloid (found in the Daturas) than those of an indole alkaloid or a tryptamine. The key reasons I'd suspect that are here:

At that point, he began to experience blurring of vision and hallucinations involving aggressive and screaming animals. Agitation and disorientation led him to seek medical assistance (he was not able to drive anymore as he was seeing giant arthropods around his car)... During hospitalization, the patient recovered rapidly with complete resolution of symptoms within 36 h post ingestion. He was unable to recall the hallucinatory period.

Despite popular opinion to the contrary, reports of cohesive imagery--possessing verisimilitude--are somewhat rare after ingestion of indole alkaloids or tryptamines. Probably a bit more common with tryptamines, from what I've read. Also, you almost never encounter reports of hallucinations that one can't distinguish from reality with those drugs. With tropane alkaloids, on the other hand, it is quite common to encounter reports of horrific imagery (although PZ might disagree on how horrific giant arthropods might be...) that one can't distinguish from reality; it's also common to not remember anything before the ingestion when one wakes up the next morning.

On the other hand, I have no idea what the active half-life of datura alkaloids is: 36 hours is a pretty long duration of activity. And the tropane alkaloids have a fairly narrow toxicity index, so you would also expect to see as many cases of fatal poisonings as you would of hallucinations. So in the end, what do I know?

Thanks to Bitwise for pointing this out.