Allis Shad Identification Guide
How to recognize the large, single-spotted allis shad and separate it from its smaller shad relatives.
Read the full Allis Shad encyclopedia entry →
Key identification features
- Deep, laterally compressed, herring-like body reaching 50-80 cm
- Silvery flanks with a blue-green to olive back
- One prominent dark spot on the shoulder just behind the gill cover, rarely followed by faint secondary spots
- Numerous fine, closely spaced gill rakers (roughly 90-130 on the lower limb)
- Deeply forked tail and a saw-edged row of keeled scutes along the belly
- Single soft dorsal fin set at mid-body, no adipose fin
Common look-alikes
- Twaite shad: has a distinct row of 4-10 dark spots trailing back from the shoulder, whereas allis shad shows only a single spot.
- Twaite shad (gill rakers): twaite carries far fewer, coarser gill rakers (roughly 30-60) than the fine, numerous rakers of allis shad.
- European sardine/pilchard: lacks the sharp keel of belly scutes and single dorsal fin position typical of shad.
Where you'll see one
Allis shad are anadromous, spending their adult lives along Atlantic European and northwest African coasts before running up large rivers such as the Loire, Gironde, and Garonne each spring to spawn in fast, gravelly reaches.
Frequently asked questions
How do I tell an allis shad from a twaite shad?
Count the spots: allis shad shows just one dark shoulder spot, while twaite shad has a row of several spots running back along the flank. Allis shad also has many more, finer gill rakers.
What is the easiest field mark for identifying a shad as opposed to a herring?
Look at the belly: shads like the allis shad carry a row of sharp, saw-like scutes along the midline that true herrings lack, along with a single dorsal fin set at mid-body.