The Tsukiji fish market is one of Tokyo’s most popular tourist attractions. It is the biggest fish market in the world. Beware though, as you need to get up very early to get a glimpse of the fish auctions.
To see the tuna auction, you need to arrive at the market around 3:45 am. There is a quota set for the number of people who can see the auction, so it is important to get there early, or you could miss out on a place. Currently the quote is set at 120 people. The subway is not running at this time, so if your hotel is not within walking distance to the market, you will need to take a taxi. The market is closed on Sundays.
Remember that the market is a place where business is being carried out and is not something just put on for tourists. It is important to respect the people working there and try to avoid flash photography.
If the auction is too early for you, the area is still worth visiting in the morning. There are many food shops and sushi restaurants surrounding the market.