Shirasu is immature fish of Japanese anchovy, sardine, eel, and pacific herring, but most shirasu caught in Japan are fry of sardine. Shirasu is caught by using dragnet, and fresh shirasu have a transparent body, which is to protect themselves from bigger fish. The size of shirasu are less than 2 cm, 0.78 inch. Shirasu are tender and the whole fish can be eaten from head to bones.
There are different kinds of processed shirasu. Shirasu which is boiled is called kamaage, and is the most popular type. When boiled shirasu is dried under the sun for about two hours, it is called shirasu-boshi. By drying the shirasu for more than half a day, it is called chirimen.
In Kanasai region, chirimen used to be most popular, and in Kanto region, shirasu-boshi used to be most popular. Kamaage is still main stream in Shizuoka prefecture where the volume of shirasu caught is highest in Japan, because the timing to boil shirasu to cook kamaage should be as quick as possible after they are caught.
Spring and autumn is the main season when shirasu are caught. Shirasu put on fat in autumn which makes the taste better, and autumn is the best season to eat shirasu. Shirasu can be eaten raw, and nama-shirasu-don, which is raw shirasu served on a bowl of rice, is popular to eat near the fishing port. However, shirasu are distributed at supermarkets all over Japan, and anyone can enjoy shirasu all year round.
Shirasu can be used for many recipes. The most popular way to eat shirasu is to put kamaage on top of rice, and soy sauce are often poured. Tempura using shirasu is a delicious side dish. By mixing shirasu with eggs and frying, shirasu egg rolls can be made.