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: Dark vertical bars down the flankAt a glance It separates Shiners and minnows from Yellow perch, young of year cleanly, and every pair of groups still in play differs on it and you can check it at a glance.
What to look at
Shiners and minnows
Yellow perch, young of year
Spiny front dorsal fin (perch, sunfish)decisiveIn hand
No
Yes
One soft dorsal fin, no spinesdecisiveClose look
Yes
No
Dorsal fin layoutdecisiveClose look
None of these
Two dorsal fins with a gap between
Dark vertical bars down the flankdecisiveAt a glance
Not diagnostic
Yes
Blunt flat head with a small mouthClose look
Not diagnostic
No
Reported size
38–230 mm
5–80 mm
Water it is recorded in
lake margin, lake open, river, stream, reservoir
lake margin, lake open, river, reservoir
Life stages covered
young-of-year, adult
young-of-year
How it moves
schooling; emerald shiners spawn at night in shallow water over sand or mud
schooling by size and age; feeding in daylight and largely inactive at night
Reference seasonality
No family-level window
Spring spawn, then shallows: Mar, Apr, May, Jun, Jul, Aug
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
no reviewed plateNo plate is drawn for this group, and that is a decision rather than a backlog item. This family is identified by what is missing — no belly keel, no spines, no adipose fin, no thread off the back fin — so a drawing of one shiner would be asserting a shape the record does not claim for the family. Read the four absences below instead. A plate becomes possible here the day this entry narrows to a named species.
Cyprinidae
Shiners and minnows
One soft fin, no saw on the belly, nothing else to it.
First check
Run a finger along the belly, look at the front of the back fin, and check behind it. No saw-edged belly, no spines and no adipose fin is a minnow.
What it is
In forage terms the plainest family: a small fish with one soft dorsal fin, no spines anywhere, no saw-edged belly and no adipose fin. Almost every identification here is made by what is absent.
Stages
Adult (38–230 mm across four common baitfish species)
Water
lake-margin, lake-open, river, stream, reservoir
Separates from Yellow perch, young of year
A spiny front dorsal fin rules out every native minnow. This is the single most useful cut in the whole forage layer.
Typical windows
No family-level window in this layer.
Patterns (correspondence)
None mapped yet.
Limits
Family-level only. Species separation within Cyprinidae is not supported here.
Two separate dorsal fins with a gap between them, a deep body flattened side to side, and bars rather than a stripe. That is a young perch; a darter is slender and nearly round.
What it is
The spiny-rayed cut is the most useful single division in freshwater forage. Minnows and herrings have one soft dorsal fin and no spines. Perch and sunfish have a spiny fin at the front. Everything else follows from that.
Stages
Young of year (About 5 mm at hatching; roughly 60–80 mm by late summer in Lakes Michigan and Erie)
Water
lake-margin, lake-open, river, reservoir
Separates from Shiners and minnows
No spines anywhere means a minnow. The spiny front dorsal is the cut.
Typical windows
Spring spawn, then shallows (young-of-year)
Patterns (correspondence)
None mapped yet.
Limits
Agency surveys in Lakes Michigan and Erie put age-0 yellow perch at roughly 60–80 mm total length by late summer and autumn. Earlier in the season they are far smaller.