First checkOne joined dorsal fin and a dark ear flap on a very deep body. That is a sunfish, not a perch.
A young sunfish is spiny-rayed like a perch, so the first cut puts them in the same half of the key. What separates them is the shape and the flap.
Sunfish are very deep — roughly half as deep as they are long — with the spiny and soft parts of the dorsal joined into one fin rather than standing apart. At the rear corner of the gill cover sits a dark opercular flap, the ear flap, which perch does not have.
They leave open water early. Fry are pelagic for a few weeks and then return to weed and cover at around twenty-one to twenty-five millimetres, and stay there.
The tell
What settles it, and what settles against it.
Read off this record's own diagnostic weights, heaviest first. A structure near the top of the left column does most of the work on its own; one near the bottom only leans.
Argues for Sunfish, young of year
Fish-shaped forage silhouette (minnow / shiner / fry) — not an insect+6
Spiny front dorsal fin, separate from or joined to a soft second dorsal (perch, sunfish)+6
Dark opercular flap (ear flap) at the rear corner of the gill cover+5
Deep-bodied and strongly flattened side to side+5
Dark vertical bars down the flank, not a horizontal stripe+4
Moving as a school or tight bait cluster, not as a single insect+2
Argues against it
One soft dorsal fin only, with no spines (minnows, shads, herrings)-5
No pelvic fins on the underside at all-5
Sawtooth belly — a row of sharp scutes along the midline you can feel-4
Small fleshy fin between the dorsal fin and the tail-4
Last dorsal ray drawn out into a long trailing thread-4
Rounded, cigar-shaped body — not slab-sided-4
Body long and thin, many times longer than it is deep-4
One dorsal fin running most of the length of the back-4
Rows of smaller spots trailing behind the shoulder spot-4
Head wide and flattened, wider than the body behind it-4
Sits on the bottom and darts — it does not hover-4
Dives into clean sand and disappears-4
Blunt, flattened head with a small mouth at the front-3
Big fan-shaped side fins the fish props itself on-3
Dark spot just behind the upper edge of the gill cover-2
Two dorsal fins with a clear gap between them-2
Body translucent — light passes through it, and the backbone or gut shows-2
Snout overhangs the mouth, its tip in front of the jaw-2
Tail fin rounded or squared off, not forked-2
Eye diameter greater than the length of the snout-1
Mouth angled upward, the lower jaw leading-1
A structure at −4 or below is treated as a hard exclusion by the comparison tool rather than as a penalty: if you saw it, this group is ruled out and no amount of matching elsewhere brings it back. Run a comparison →
Life stages
What it looks like, stage by stage.
Sunfish, young of year — Young of yeardrawn
Young of yearthe stage a fish meets
Size in hand21–50 mm in the first year
What you see
Spiny and soft dorsal joined into one fin, or divided only slightly
Dark opercular flap at the rear of the gill cover
Three or more spines at the front of the anal fin
Vertical barring prominent on young fish, fading on adults
Where it turns up
Pelagic as fry, then in and around weed and cover in warm quiet water.
How it moves
Holds in cover rather than schooling in open water.
Cues this stage offers the comparison
Fish-shaped forage silhouette (minnow / shiner / fry) — not an insect
Spiny front dorsal fin, separate from or joined to a soft second dorsal (perch, sunfish)
Dark opercular flap (ear flap) at the rear corner of the gill cover
Deep-bodied and strongly flattened side to side
Dark vertical bars down the flank, not a horizontal stripe
Confused with
Telling it from what it isn't.
Sunfish, young of yearvsYellow perch, young of year
Two separate dorsal fins with a gap, and spines on the gill-cover tip, is a perch. Sunfish has one joined fin, an ear flap, and no opercular spines.
These groups name Sunfish, young of year in their own separators. If you arrived holding one of them and were not sure, this is the sentence that pointed you over.
Cisco / lake herringsaid
A spiny front dorsal fin and a dark ear flap is a young sunfish. Cisco has soft rays only.
Where in the column it mattersNear the bottom. Fry are pelagic for several weeks, then return to weed and cover at around twenty-one to twenty-five millimetres and stay there. After that they are a cover animal, not an open-water one.
Read from the record's own position notes: fry stay pelagic for several weeks; then move to littoral vegetation at about 21 to 25 mm; warm quiet water with at least moderate vegetation.
What eats it
Which fish the dossiers actually name.
No reviewed dossier names this group. That is an absence in the dossier layer rather than a finding about the animal — four dossiers exist and only one of them names any forage group at all.
Nothing in the pattern layer is mapped to this group, so no presentation family follows from it here.
Not known
What this entry cannot tell you.
9 of them. The limits are part of what was reviewed rather than a disclaimer bolted on afterwards. An entry that hid them would be claiming more than it checked.
Written by the reviewer
Declared by the reviewerFirst-year bluegill average roughly 25–50 mm; fry return from open water to cover at about 21–25 mm.
Declared by the reviewerThis entry covers Lepomis broadly. Separating bluegill from pumpkinseed or redear as young fish is not supported here.
Declared by the reviewerThe separation from a young perch is assembled from family characters. No source consulted made that comparison directly.
Declared by the reviewerFirst-year bluegill average roughly 25 to 50 mm; fry return from open water to weed cover at about 21 to 25 mm.
Declared by the reviewerThis record covers Lepomis broadly; separating bluegill from pumpkinseed or redear as young fish is not supported here.
Declared by the reviewerSeparating a young sunfish from a young perch is assembled from family characters; no source consulted made the comparison directly.
Read off the record
Nobody typed these. They are fields that are empty, said out loud rather than left for you to notice from a section that simply is not there.
SeasonalityNo reference window is published for this group, so this entry says nothing about when it is available. That is an absence in the calendar layer, not a claim that the animal has no season.
PatternsNo fly pattern in the pattern layer is mapped to this group. Whether anything imitates it is not answered here.
What eats itNo reviewed species dossier names this group. Some dossiers describe forage in class terms — small forage, insects, bait — and those are shown below, but a class description is not a reviewed link to this group and none is claimed.
Sources
Everything above rests on 6 published pages.
Attribution here is to the whole record, not to individual sentences — the carrier attaches a source set to a record and does not say which page carried which line. Naming one per claim would mean inventing a mapping nobody reviewed.
A plate shows shape. It cannot show a gill beating, a mask firing, or an animal reversing into sand — so where motion is the field mark, the entry points at motion. These are demonstrations, selected by hand and by publisher. Nothing here is a source: it changes no score, no window and no reviewed claim.
Engbretson Underwater Photography. The deep slab-sided body turning edge-on to nothing and back to a full disc, and the dark ear flap flaring.
Working biologist · external video · title read back from the publisher 2026-09-09
Carry it on
Take the group to the next step.
These send the class of animal and the water this record is documented in. They do not send a sighting, because this page does not have one — you have not told it what you saw.
Which fish in this kind of water are documented eating this class of forage, and how they behave when they are.
What this forage class asks of the setup — the weight it wants, and where the chain gives first.
Keep the group on the day's record, so a later entry can be compared against what you were looking at.
Found an error?
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