> Hallucinogenic fish can be contrasted with psychedelic fish. Psychedelic fish do not produce hallucinations if eaten, but look as if they were the product of a psychedelic hallucination.
I could say "I feel like I spent all day doing code reviews," meaning that I probably did other things too, but the volume of code reviews was draining, so the small amount of other things that I did were less noticable.
Using "feel like" in that context is accompanying the hyperbole that follows. The mods aren't literally fighting a torrent of spam/bad content, but there probably is a lot of it, so it "feels" more extreme
does anyone know why we can't tell what substances cause the hallucinogenic effects? to a complete layman (i.e. me) this seems like the kind of thing modern science should be able to determine
For a good example of historically what it took, check out the story of how Hoffman isolated psilocybin from psychedelic mushrooms:
So ultimately it comes down to whether people have put in the time to isolate the various alkaloids and then determine which ones are psychoactive.
 https://en.wikipedia.org/wiki/Echinopsis_pachanoi#Alkaloids In San Pedro cactus for example, there have been a dozen that were extracted, isolated and identified.
It sounds like Hoffman was eager to find more hallucinogens after discovering LSD.
Here is a .pdf copy of the book from MAPS: 
If you're interested in the history of this stuff, it's well worth a read.
More generally, I think many exceptional drug chemists have been willing to bioassay the novel drugs they make. Almost inarguably the most prolific drug chemist of all time, Alexander Shulgin, bioassayed over 200 novel drugs, making him the first human being to try almost all of them. What is most interesting about Hoffman in this regard is that he didn't set out to be a drug chemist: he discovered LSD was psychoactive on accident. So his temperament (with regard to his willingness to bioassay novel compounds) was a fortuitous coincidence.
Take cannabis, for example: the endocannabinoid system in our central and peripheral nervous systems effects a variety of things (memory, sleep, appetite, etc.) but it's also useful to plants, which evolved the system roughly 500 million years ago, independently of animals.
In higher lifeforms, e.g. animals, some of these intracellular signalling chemicals have been repurposed to become intercellular signalling chemicals within specific tissues. However, these molecules continue to act as intracellular signals within cells; it is often the reaction of the cell to the intracellular stimulus that is perceived by a larger group of cells as the intercellular stimulus.
Animals have developed advanced tissue isolation, circulatory, and xenometabolic mechanisms to prevent parasites and predators from injecting these "intercellular but actually intracellular" signals into arbitrary places in the body, because—sort of like every microcontroller having JTAG pins—every cell is "listening" for these signals, and might do something stupid/unplanned in response if the body wasn't evolved to ever emit them into such tissue. Best to put up some firewalls to hide all these open ports. This also allows you to use the same signal to mean different things in different componentized tissues (e.g. how serotonin acts in the gut vs. in the nervous system.)
But these firewalling mechanisms, e.g. the blood-brain barrier, are themselves simple, inherited from pretty early on in the multicellular tree of life. So they mostly just block the simple, active forms of these molecules—the ones the body uses itself.
So, in other words, for an organism to evolve a novel poison, it just has to take its own signalling molecules—which it already knows how to make, and shares in common with pretty much everything else—and then evolve some enzyme that "tags" that molecule in such a way that most evolved barriers won't stop it, and also in such a way that it will either break down on its own, or will break down in response to other molecules floating about in the target area, back into the signaling molecule. Boom—toxin.
It's also pretty easy to take the gene you use for creating a signalling molecule, copy it, and let the copy mutate so it now produces a deformed version of the signalling molecule—one that locks into the same receptor, but either doesn't activate the receptor, or is excitotoxic to the receptor, or isn't recognized by the various -lyzes and -ases which organisms evolve to garbage-collect signals.
Keep in mind, most of the time, these kinds of poisons will be maladaptive, because the produced toxin will end up attacking the host's own body; but if the gene happens to only get expressed in tissues of some gland (e.g. the salivary gland), then it has room to evolve into a venom.
Evolving to be poisonous is a bit harder, I think; it needs to coincide, or maybe be preceded by, the evolution of a barrier to similar toxins, e.g. skin that won't absorb the poison produced by your own sweat glands. Most poisonous animals probably preyed upon another poisonous or venomous plant/animal at some point, and evolved the defence first, before either harnessing that toxin from their food, or evolving something similar themselves.
I wonder why this fish hasn't been 'mined' for its hallucinogenic properties yet. Surely some of the more adventurous drug users would jump at a chance to try something this powerful? The article on the fish itself seems to state that it was available in restaurants, so it's not exactly a rare find, I assume.
Unviable as a street drug.
Drinking a liter of vodka in one go without having any experience with alcohol also potentially causes extreme delirium and confusion, yet people drink alcohol all the time and are mostly fine.
But with that said, I would strongly caution people not to take tropane deleriants. Unless you really know what you're doing, there's a solid chance you are going to end up being high for way too long or end up in the hospital.
I'll also caution codr7 that seeds (especially from different sources) can have hugely different potencies, so be careful dosing anything via seed, especially something as serious as datura. It sounds like this works for you, so I don't intend to sound patronizing: I just want to make sure that I am spreading harm reduction everywhere I go, and datura/tropane alkaloids can be very dangerous.
What kind of instruments did you use?
Never did get around to trying 2CB-Fly...
Among the the empathogenic benzofurans, the APBs you listed seemed to be "gems in the rough" so to speak; most of the others ended up in flavor-of-the-month "Benzofury" blends and were quickly forgotten about.
By the time I got my hands on any 2CB-FLY my life was moving on and I never did try it. Oh well, I had fun...
As someone that did a lot of stuff in their youth , I strongly say no thank you.
 I mentioned some of the good and bad experiences recently in this comment https://news.ycombinator.com/item?id=22225541
As a random aside, I dated a professional mermaid (kids parties, adult parties)/mermaid sex worker (cam mostly) briefly several years ago. scales tattooed on her face, had a few different tails... yeah, even if I was out to sea for months I don't think a real mermaid (or the hallucination of one) would get me all hot and bothered. The tails and general mermaid themed decor was a bit much.
String theory much?!