The comparison scores every group at once. This page is for the moment you already have a pair of names in mind — mayfly or stonefly, scud or sowbug, shad or alewife — and want the structures that keep them apart, in one look. Nothing here is a current hatch.
The differences, and nothing else
Best separating check: Deep, slab-sided bodyAt a glance It separates Mullet (young) from Menhaden (bunker, pogy) cleanly, and every pair of groups still in play differs on it and you can check it at a glance.
What to look at
Mullet (young)
Menhaden (bunker, pogy)
Dorsal fin layoutdecisiveClose look
Two dorsal fins with a gap between
None of these
Blunt flat head with a small mouthdecisiveClose look
Yes
No
Rows of small spots behind the shoulder spotdecisiveClose look
No
Yes
Sawtooth belly keel you can feeldecisiveIn hand
No
Yes
Deep, slab-sided bodydecisiveAt a glance
Not diagnostic
Yes
Rounded, cigar-shaped bodydecisiveAt a glance
Yes
No
Spiny front dorsal fin (perch, sunfish)decisiveIn hand
Yes
No
One soft dorsal fin, no spinesdecisiveClose look
No
Yes
Reported size
15–698 mm
30–500 mm
How it moves
leaps clear of the water, sometimes a metre up; one of its common names is jumping mullet; schools by day for protection
dense schools that ripple or splash at the water surface; young fish corralled at the surface or tight to the shoreline in a feeding blitz
Reference seasonality
Autumn migration: Sep, Oct, Nov
Inshore season: May, Jun, Jul, Aug, Sep, Oct
The same for both: water, life stages.
Rows come from the reviewed diagnostic weights the comparison scores with. “Decisive” means one answer puts them at least four points apart — the carrier's own rule for a structure that separates a pair.
The two entries, side by side
Mugil cephalus, Mugil curema
Mullet (young)
Blunt head, small mouth, two back fins, and a habit of leaving the water for no reason anyone can prove.
First check
Look at the head end. Blunt, flat, and a small mouth at the very front, with two widely separated back fins behind it — mullet.
What it is
Mullet are the one fish in this wave that everybody has watched and almost nobody has looked at. They jump — sometimes a metre clear — and four different agencies give four different explanations for why. To evade predators. To clean the gills. To get oxygen out of warm stagnant water. And, from Connecticut, with admirable directness: for unclear reasons. Four sourced answers and no settled one is a perfectly good thing for a field guide to say.
Stages
First year (15–178 mm; pre-juveniles reach the outer beaches at 20–25 mm and enter North Carolina estuaries at about 22 mm) · Full-grown (283–698 mm for North Carolina striped mullet (males mature at 283 mm, females at 319); white mullet are common only to about 330 mm; larger maxima published elsewhere)
Water
surf, inshore, nearshore
Separates from Menhaden (bunker, pogy)
One dorsal, a sawtooth belly and a shoulder spot is menhaden. No consulted source makes this comparison directly — it is assembled character by character, and is flagged as such.
Typical windows
Autumn migration (adult)
Patterns (correspondence)
None mapped yet.
Limits
The phrase “mullet run” is used by no source consulted; North Carolina records fishermen calling the movement a “mullet blow”. “Finger mullet” is North Carolina's name for young-of-year mullet.
Everyone knows the shoulder spot. The shoulder spot is not the answer.
First check
Find the shoulder spot, then look BEHIND it. Rows of smaller spots trailing back is menhaden. A single spot on its own settles nothing.
What it is
A menhaden is a deep, slab-sided, oily fish with a head about a third of its body, swimming with its mouth open and straining plankton through a basket of gill rakers. In a school they ripple and splash at the surface, and when something is under them the young ones get corralled tight to the shoreline in what Massachusetts calls, in an official publication, a blitz. That is the animal most of the coast is actually fishing over.
Stages
First year (30–150 mm; the NOAA staging runs larva under 30, prejuvenile 30–38, juvenile above 38) · Full-grown (152–500 mm depending which source you read — see the limitations)
Water
surf, inshore, nearshore
Separates from Mullet (young)
This entry does not name Mullet (young) as a look-alike. That is a gap in the prose, not proof they cannot be confused.
Typical windows
Inshore season (adult)
Patterns (correspondence)
None mapped yet.
Limits
Adult size is stated five incompatible ways across five agencies, one of them exceeding another's stated maximum.