The logic is simple. Fish, especially sushi, should be served as fresh as possible and not many fishermen catch fish on a Sunday - or Saturday, or Friday for that matter - which is why it's widely speculated that the fish you buy on a Monday can often be four or five days old.

The traditional advice to avoid sushi on Mondays stems from a time when fish markets (like Tokyo's Tsukiji) were closed on Sundays, meaning Monday's fish was likely caught on Friday or Saturday and was nearing the end of its peak freshness. This warning was famously popularized by Anthony Bourdain in his 2000 book Kitchen Confidential. However, in 2026, this is largely considered an outdated myth for high-quality restaurants. Modern logistics and advanced "super-freezing" technology at -60°C allow premium fish to be transported globally and kept in "fresher than fresh" condition regardless of the day. Furthermore, many elite sushi chefs actually prefer "aging" certain fish (like tuna) for several days to develop umami flavors. While you might avoid a "budget" supermarket sushi tray on a Monday afternoon, any reputable 2026 sushi bar with daily air-freighted deliveries is perfectly safe and delicious seven days a week.