Masago is processed fish eggs, also known as roe, that come from a small fish called capelin. The capelin exists in massive quantities in the Atlantic and Pacific oceans.
Masago is bright orange in color and has a reddish tint to it. It is often used to coat the outside of sushi rolls. It is also used in making sushi fillings.
Masago is often confused with tobiko. Tobiko is also fish eggs, but they are notably larger in size and lighter in color than masago. They taste similar, but their texture is not the same. Tobiko comes from flying fish.