A kipper, is a whole fish that has been split from tail to head, gutted, salted, and cold smoked.
Typically, the species is a herring or salmon, but traditionally it is any fish found in great numbers and caught during its spawning period. Spawning fish are not good to eat fresh and usually arrive in great abundance, thus they are salted and smoked to improve flavor and preservation.
A red herring is a whole unsplit fish. Red herring can be served cold, sliced thinly across the body with new bread and butter or a salad as a starter. In the UK and the eastern seaboard of North America they are often eaten grilled for breakfast.