Opisthonema
Opisthonema is a genus of herrings, the thread herrings, found in tropical waters of the Western Hemisphere. They get their name from a filamentous nature of the last ray of the dorsal fin. Currently, five species are in this genus. Species
 Opisthonema berlangai Berry & Barrett, 1963 (Galapagos thread herring)
 Opisthonema bulleri (Regan, 1904) (slender thread herring)
 O. libertate (Günther, 1867) (Pacific thread herring)
 Opisthonema medirastre Berry & Barrett, 1963 (middling thread herring)
 O.oglinum (Lesueur, 1818) (Atlantic thread herring)

References
 

Opisthonema
Marine fish genera
Taxa named by Theodore Gill