"Shirouo are very small transparent fish destined to be eaten alive. They dance in your mouth - or rather do the odorigui (dancing while being eaten) as the locals in the few places where you can enjoy the fish put it.
The cute little fish will arrive on your table in a big bowl, darting through the water and most likely dreaming about sex. It's their annual mating habit that has them swimming up the river, and getting them into the trap that brought them to your table.
Along with the bowl of fish come a quail egg and a bottle of vinegar. You crack the egg and pour it into the cup provided, then mix it with some vinegar.
Then, you start the delicious cruelty with a device which is half ladle half sieve, you catch some of the fish out of the bowl and throw them into the smaller bowl of quail egg / vinegar mix. Locals will tell you that the vinegar is numbing the fish, rendering it unconscious. But if you look at the proceedings yourselves, you will discover that the vinegar may be pure torture to the poor little beast - it wriggles like crazy.
Now, you catch the little fish with your chopsticks, look at it while it hopelessly wriggles for its life, and no, you don't walk out to the nearby river to put it back home. You put it into your mouth. And let it dance. It's quite a sensation to have the little devil jump through all of your oral cavity. He tingles your tongue, he might jump at sensible taste nerves never touched in years. This doomed little guy may even reach pleasure zones you didn't know you have in your mouth! Cruelty can be so beautiful! Let him jump around in your mouth just a little more!ventually, of course, the question arises… To Swallow or Not to Swallow? I always preferred to crush the little beasts between my teeth. Killing them brutally but sparing them any further discomfort.
My Japanese friends tend to swallow them alive… and then tell me that they swim freely through their stomach and irrite their intestines, which was of course always a great excuse for drinking large cups of strong shochu to get rid of those strange feelings deep inside their bellies.
I always joined them on the shochu … a great way to finish off an afternoon of exquisite pleasure."
Text from japanvisitor.com