(Oh, and in case you think I’m a monster, no I didn’t agree to the dish; she just ordered it without telling me what was going to happen)

Not long, it’s dying (suffocating actually, because it has no muscles left to drive water through its gills.

I’ve actually eaten this (at my girlfriend’s instigation) and I can fill in some details:

1. Yes the fish bleeds, it’s put back into the tank for a few minutes essentially to wash it while the chef prepares the fillits for the sashimi

2. Yes the fish feels pain (unless you’re one of those stupid English anglers who insist that fish don’t)

3. When I had it, the fish was retrieved from the tank, skewed and then placed as decoration on the plate in front of us. This is apparently a pretty common way of preparing this dish

4. It’s not hard to find. We had it in central Tokyo at a sushi place that is not a lot above a tourist trap (although many Japanese eat there). Apparently, you just have to ask - but like many things in Japan you might need to be accompanied by a local who will vouch for you. The Japanese often don’t expose gaigen to the more extreme aspects of their culture, they don’t want foriegners making a fuss or being impolite.

5. Yes - it is very emotionally confronting. I’m not sure what my girl’s motivation was, I haven’t bothered to ask - and I was very surprised as she is bhuddist.