土用の丑の日には「う」のつく食べ物を食べますが、その中でも特に有名なのは「鰻」です。鰻のシーズンは秋なので、夏にはあまり魚屋さんなどにありません。最近は養殖の鰻が多いので、一年中鰻を買うことができます。
During doyou no ushi no hi, we eat foods that begin with う. Among those the most famous is unagi (eels). Unagi season begins in the fall, so not many fish markets have them in the summer. These days there are many farmed eels, so it is possible to buy them year-round.

夏には脂肪が多い魚が少ないですが、鰻は脂肪が多く、ビタミンも多いです。土用の丑の日に、鰻を食べて暑い夏でも頑張ろうという事ですね。
In the summer there aren’t too many fish with lots of fat. However, eels have lots of fat and vitamins. During doyou no ushi no hi, it is said that eating eels will help you work hard through the summer heat.

土用の丑の日の前には、スーパーや魚屋さんで「鰻の予約開始中」というお知らせを見ます。昔から続く習慣が今でも残っているのは面白いですね。ちなみに、福井県では半夏生(夏至から１１日目の日)に鯖を一人一本食べるという風習があります。これも土用の丑の日の鰻と似ている理由で、鯖には良い栄養がありますから、田植えが終わって疲れた農民が食べたそうです。でも一人一本はちょっと多いですね！
Before doyou no ushi no hi, you can see signs at supermarkets and fishmongers calling for eel reservations. It’s interesting to see these old customs continuing even today. By the way, in Fukui, on hangeshou (the 11th day after the summer solstice) there is a custom for each person to eat one whole saba (mackerel). This is for a reason similar to why people eat eels during doyou no ushi no hi. Mackerels have lots of nutrition, so farmers would eat them after the planting was done. But one whole fish per person seems a bit too much!