This form of dried fish is used very widely in East and Southeast Asia. They come in many sizes, the photo showing some of the smallest (0.68 inch long) and largest (2.5 inches long) common sizes. These were purchased at a Korean market in Los Angeles. The small ones are often crushed to paste with some water to make an impromptu fish sauce for use in soups, stir fries and the like. The larger are used to make Korean Anchovy Stock, a very important basic ingredient.
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Buying: These dried fish are most plentiful in Korean markets, packaged in small plastic bags.
Storing: Keep dry in a very tightly sealed container. If they came with a packet of dehydrator, include it in the container.
Cooking: The large dried anchovies usually have the guts scraped out before use to make stock, or the stock will be a bit sour. Some people remove the head, others do not. The fish are discarded after the stock is made.