Sprattus sprattus grows up to 16 cm in length. It is shiny silver to grey in colour. It has a very forked tail and small and angular anal and dorsal fins. The dorsal fin is directly above the pelvic fin. The head is small and the lower jaw is upturned and projects slightly.Sprat may be confused with juvenile herring. The relative positions of dorsal and pelvic fins, the grey rather than blue coloration on the dorsal side and the sharply toothed ventral keel are, however, clear distinguishing features.