Migratory fish are species of fish that travel long distances between their spawning, feeding, and nursery grounds. ELVER, with five letters, is a young EEL, which is a type of migratory fish. EEL, with three letters, is an elongated fish that can be found in both freshwater and saltwater habitats. SHAD, with four letters, is a type of herring that migrates up rivers to spawn. All of these fish migrate long distances to complete their life cycles.