Twaite Shad Identification Guide
How to spot the row of shoulder spots and other marks that identify twaite shad in the field.
Read the full Twaite Shad encyclopedia entry →
Key identification features
- Moderately deep, laterally compressed body, typically 30-50 cm
- Silvery sides with a greenish-blue back
- A row of 4 to 10 dark spots running back from the shoulder along the upper flank
- Coarse, widely spaced gill rakers (about 30-60 on the lower limb)
- Deeply forked tail fin and a keeled row of scutes along the belly
- Single dorsal fin positioned at mid-body, no adipose fin
Common look-alikes
- Allis shad: shows only one shoulder spot instead of a full row, and has many more, finer gill rakers than twaite shad.
- Atlantic herring: lacks belly scutes and any row of dark shoulder spots, with a smoother, unkeeled ventral profile.
- European sardine: has a blunter snout and lacks the diagnostic spot row and sawtooth belly of twaite shad.
Where you'll see one
Twaite shad are anadromous fish of the eastern Atlantic and Mediterranean, living along coasts and in estuaries before ascending rivers in spring to spawn over gravel or sand in slower-flowing stretches than those preferred by allis shad.
Frequently asked questions
How can I tell a twaite shad from an allis shad at a glance?
Check the flank behind the gill cover: twaite shad shows a row of several dark spots, while allis shad typically has just a single spot and noticeably finer, more numerous gill rakers.
What separates twaite shad from a herring?
Twaite shad has a row of dark spots along the upper side and a sharp, saw-edged keel of scutes on the belly, both of which are absent in true herrings.