Tsukiji fish market was amazing. It's a small city, estimated to have around 60,000 people who work there. It's interesting that they're not quite sure, since most people who are there work in independent businesses.
Here's a short video clip of tuna being auctioned at the famous Tsukiji Fish Market in Tokyo, the world's larget. There are two auctioneers working at once, the singing sounds are the voices of the auctioneers. Note the differences in their voices, to work near each other they have distinct styles, one more uniform and the other with a repeating rhythmic sound.
There are some amazing fish being sold, I wonder how much for this fish that looks to be a 300 kg (660 pound) bluefin tuna? There are hundreds of tuna in this room on this day, you can see them spread out on racks that go perhaps 100 meters into the distance. There's another room in the other direction that has nearly this many tuna in it also. I'm not sure how many tuna overall, but well into the hundreds and perhaps over a thousand. Just one day's business in Tsukiji.
Walking around the fringes of the market, you can find retail stalls selling anything. Here are some whole dried sardines, at 2000 yen per kilogram (about 10 US dollars per pound). Whatever you like, I'm sure you can find it here.