Ok, this is really ust a thought, let me know if it's dumb. I remember reading on here that someone said they reachd theior hand into water with a dead blue ring and experienced numbness...do you think that this could be used for anesthesia or something like that? That is, if they could isolate the numbing agent from the TTX I guess...I don't know, just a thought.
It's actually a pretty good thought, but I think TTX is too good at what it does... it's used a lot for research, because it temporarily (for hours or days) blocks voltage-gated sodium channels in all nerves it's exposed to (except cardiac nerves, for some reason) which pretty much shuts them down completely... this is very useful for researchers who want to see the way nerves break when they can't use sodium channels (usually applied to a nerve or ganglion sitting in a dish outside the animal, or these days just nerve channels produced by splicing the gene to grow them in a Xenopus
frog egg), but it's so good at blocking them that it completely shuts down the nerves it's exposed to, so the challenge to use it on patients would be that it's hard to limit it's scope. Right now, once it's in the bloodstream, it shuts down everything
except the heart and brain (because it can't cross the blood-brain barrier) so although it makes the whole body numb, it also makes the whole body flaccidly paralyzed so it can't breath, or do anything else (digest food, cough, etc.)
TTX is actually a wonderful way to study voltage-gated sodium channels, because it doesn't permanently block the channel, so you can go back to the old configuration, and there are known mutants of the channels that are resistant to it, so studying the changes in structure that make the channel not susceptible to TTX blocking can lead to all sorts of insights into what the function of parts of the channel are, and the techniques to express cloned genes for these channels in frog eggs makes it convenient to work with them.
Blue rings and other TTX-using animals have modified sodium channels that are resistant to TTX as well; I know the cardiac TTX-proof channels from rats have been cloned, but I'm not sure if it's known if the modifications in blue rings, puffer fish, and newts are the same as the ones in rat (or human) cardiac channels. I'd hope this is being studied, since the voltage-gated sodium channel is really one of the "keystone" trans-membrane proteins being studied to understand how they work in general, since it's pretty similar across all animals, and it's a good example of many similar systems, like all of the neurotransmitter receptors that drugs like antidepressants work on.