Niboshi are dried baby sardines. They can be used for making dashi, and snacks. Because niboshi are whole fish, albeit small, they still have their innards, and heads attached. The head and stomach tend to leave a bitter fishy after taste when used in dashi so I prefer to remove the head and stomach, and use it in making furikake. Removing everything is really easy especially in small batches, here's how.
1. Take off the head
2. Split the body in half along the spine by applying pressure to the stomach and pulling apart