Species & PresentationHook the Horizon · field intelligence

Other freshwater · Freshwater

Mooneye

Hiodon tergisus

Native cool-water hiodontid of clear rivers and shallow lake waters in central and eastern North America.

Also called moon eye, toothed herring (misapplied).

  • Flowing water
  • Stillwater
  • Ordinary target
  • 4 of 4 overlays reviewed
  • Reviewed 2026-08-27
10 things this record does not know

Take this somewhere

This page is the record. The reading is what happens when you add water, a season and a temperature to it — that is where the families below get ranked against each other instead of just listed.

Start a readingRead Mooneye on your waterOpens the analyst with this fish already picked.Forage & hatchHatch MatchWhat this fish is likely eating on that kind of water, at that time of year.TackleTackle Link AnalystWhether the line and terminal end you already own can deliver these families.WaterField Sense NavigatorWhere water like this exists, and what it is doing right now.

Those three links carry the fish and nothing else. No conditions were declared on this page, so none travel, and the link says so rather than sending an empty reading.

The half nobody publishes

What this record does not know

Everything else on this page comes from a named agency or peer-reviewed source. This is the other side of that: the questions a reviewer went looking for an answer to and came back without, and the fields the record leaves empty because filling them would mean guessing.

It is here rather than at the bottom because a page that only shows what it knows is easy to read as a page that knows everything. For Mooneye there are 10 of them.

Named by a reviewer

7

Somebody looked for this and wrote down that they did not find it.

Behaviour

Nobody has sourced:

  • species-specific angling-pressure response beyond general cover/light notes
  • cold-front / barometric response with primary-source support
Identification

Nobody has sourced:

  • longevity as a structured field
Forage

Nobody has sourced:

  • finer month-by-month diet inside a season, which is waterbody-specific
  • quantified goldeye vs mooneye fish-fraction comparison
Season

Nobody has sourced:

  • month-by-month location changes inside a season, which are waterbody-specific
  • population-archetype calendars beyond the species-level overlay (see RPC)

Absent from the record

3

No reviewer wrote a gap here. The field is simply empty, which is its own answer.

Water temperature

No agency or peer-reviewed temperature band for Mooneye was found that a review would accept. The reading runs without one rather than borrowing a number from a related fish.

Identification

No reviewed image. A photograph is only in this catalog when an agency or a named creator labelled the subject, and nobody has cleared one for this species yet.

Population context

No regional population profile is registered. The species-level reading stands on its own; it does not silently become a local one.

Where the record puts it

Water and range

Southern Ontario and connected central/eastern North American river systems, including portions of the Great Lakes and Mississippi basins.

Flowing water

5 reviewed holding classes
  • Run
  • Pool tail
  • Current break
  • Seam
  • Deep pool

Stillwater

4 reviewed holding classes
  • Shallow flat
  • Rocky shoreline
  • Inlet
  • Drop-off

DepthUpper-to-mid column while feeding, with deeper pool use when bright, cold, or inactive.

Moving waterUses clear river runs, pool margins, and current breaks, generally with less affinity for highly turbid water than goldeye.

LightFeeds visually and can use low-light surface windows, but clear-water populations may remain active through daylight.

Thermal band

Temperature

No reviewed temperature band

Nobody publishes a preferred or active temperature range for Mooneye that a review would accept. Borrowing one from a related fish would look like knowledge and behave like a guess, so the reading runs without it and says which parts of the answer that weakens.

How it uses water

Behaviour

Loose groups in clear river runs and connected waters; not a cisco-style pelagic school as the default.

Visual feeder on drifting insects and available small prey. Minnesota DNR notes fly-caught fish during mayfly hatches on some rivers — that is a documented feeding window class, not an inference that a hatch is occurring.

Can use low-light surface windows, but clear-water populations may remain active through daylight.

Depth movementUpper-to-mid column while feeding, with deeper pool use when bright, cold, or inactive.

Facing the currentUses clear river runs, pool margins, and current breaks, generally with less affinity for highly turbid water than goldeye.

ClarityClearer-water identity than goldeye. Superficial similarity does not transfer turbidity preference.

CoverRuns, seams, and pool tails rather than vegetation ambush.

Open waterConnected lakes and large pools; still more river-run than pelagic-basin.

Predator avoidanceDepth and current more than stain, relative to goldeye.

Spawning (conservation context)Spring to early-summer spawner in river and connected-water habitat. Timing varies with latitude and flow. Sites are not named.

Where the general rule stops

  • Do not infer goldeye-style turbidity preference from superficial similarity.

What it can eat

Forage

A capacity list, not a report from this week. What is actually available on your water is a separate question, and Hatch Match is the tool that asks it.
  • Aquatic insects
  • Emerging insects
  • Terrestrial insects
  • Small forage fish
  • Crustaceans

More insectivorous and more associated with clearer water than goldeye. Small fish remain possible but are not the default adult identity.

Feeding style
Opportunistic
Feeding zone
Surface

Through the year

Winter
Subsurface invertebrates in pools.
Spring
Aquatic insects as water warms. Spawning is conservation context.
Summer
Drift, emergences, and terrestrials in runs and pool tails.
Fall
Remaining insects.

By life stage

Young of year
Zooplankton and tiny insects.
Juvenile
Aquatic insects.
Adult
Aquatic, emerging, and terrestrial insects; small fish less central than in goldeye.

Ontogenetic shiftRemains insect-weighted more than goldeye at comparable size.

SubstitutionsClearer rivers keep insect identity. Do not copy goldeye’s stronger fish fraction onto this record.

Diet capacity is not proof that a hatch or prey event is occurring. Observed current forage still comes from a user observation or Hatch Match.

Through the year

Season

Mooneye stay with clearer runs and pool margins than goldeye. The calendar is insect-drift shaped rather than turbid-surface shaped.

Winter

Where they sit
Deep pools.

What that changesDead-drift and swing.

Spring

Where they sit
Runs, seams, and pool tails.

What that changesDead-drift, surface-drift, and swing.

Spring to early-summer spawner. Timing varies with latitude and flow.

Summer

Where they sit
Clearer runs and current breaks.
Forage
Drift, emergences, and terrestrials.

What that changesDead-drift and surface-drift. Surface-retrieve in still water.

Fall

Where they sit
Pool tails and seams.

What that changesDead-drift and cross-current retrieve.

Spawning · Spring, Early summer

Spring to early-summer spawner in river and connected-water habitat; timing varies with latitude and flow.

Recorded as conservation context. No spawning site, staging concentration or migration bottleneck is named anywhere in this catalog, because naming one is how a population gets fished out.

Telling it apart

Identification

Silver sides, darker back, large pale eye. No gold iris.

What to look at

  • Silvery-white iris rather than gold.
  • Dorsal fin usually 11–12 rays, originating ahead of the anal-fin origin.
  • Ventral keel shorter — does not extend forward to the pelvic fins.
  • Generally associated with clearer water than goldeye.
Average adult length
Common adults often 9–14 in.
Common angling size
10–13 in.
Typical weight
Often well under 1.5 lb.
Maximum documented
Minnesota DNR: state-record mooneye 1 lb 15 oz (Minnesota River). This is not a goldeye maximum.

What it gets confused with

Goldeye
Goldeye: gold iris, 9–10 dorsal rays, keel extending beyond the pelvics, more turbidity-tolerant.
Cisco
Cisco have an adipose fin and a terminal mouth without a hiodontid keel.

What follows from all of that

Presentation families

These are the families the record will consider for this fish, and what each one has to do. They are not ranked here — ranking needs a season, a temperature and a piece of holding water, which is what the reading is for.

Flowing water

Dead drift

Allow a food-form imitation to move at or near current speed through a defined feeding lane.

  • controlled depth
  • minimal drag
  • short-to-medium presentation lane
  • occasional repositioning
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Short to moderate
Weight range
1/64–1/8 oz or unweighted fly
Cover resistance
Low
Line visibility
Low
Retie frequency
Moderate

Surface drift

Present a floating food form in a feeding lane with as little drag as the water allows.

  • slack management
  • reach or mend
  • dead or micro-twitch
  • leave it in the lane
What it asks of the tackle
Depth control
Surface
Sensitivity
Moderate
Casting distance
Short to moderate
Weight range
Unweighted
Cover resistance
Low
Line visibility
Low
Retie frequency
Moderate

Swing

Let current carry a bait or fly across a lane so it broadens and lifts at the hang.

  • downstream quartering
  • controlled belly
  • hang-down pause
  • slow lift
What it asks of the tackle
Depth control
Moderate
Sensitivity
Moderate
Casting distance
Moderate
Weight range
Unweighted to 1/4 oz
Cover resistance
Low
Line visibility
Moderate
Retie frequency
Low

Cross-current retrieve

Represent mobile prey crossing or holding near a current boundary.

  • horizontal travel
  • intermittent pause
  • depth retention
  • controlled acceleration
What it asks of the tackle
Depth control
Moderate
Sensitivity
Moderate
Casting distance
Moderate
Weight range
1/8–3/8 oz
Cover resistance
Moderate
Line visibility
Low
Retie frequency
Moderate

Stillwater

Horizontal retrieve

Move a swimming bait through a chosen depth band along structure or open water.

  • count down
  • steady or pulsing retrieve
  • keep the band
  • cover the edge
What it asks of the tackle
Depth control
Moderate
Sensitivity
Moderate
Casting distance
Moderate to long
Weight range
1/8–1/2 oz
Cover resistance
Moderate
Line visibility
Low
Retie frequency
Low

Surface retrieve

Work a floating bait across shade, weed edges, or low-light shallows.

  • walk, pop, or crawl
  • pause in holes
  • keep it on top
  • cover the edge
What it asks of the tackle
Depth control
Surface
Sensitivity
Low
Casting distance
Moderate
Weight range
1/4–3/4 oz
Cover resistance
Moderate
Line visibility
Moderate
Retie frequency
Low

Stop-and-go

Imitate injured or hesitating prey by mixing travel with pauses that hold the bait in the strike zone.

  • travel
  • pause
  • keep depth on the pause
  • restart without jumping the band
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Moderate
Weight range
1/8–3/8 oz
Cover resistance
Moderate
Line visibility
Low
Retie frequency
Moderate

What moves them for this fish

Reviewed rules that push particular families up when the conditions match. Each one names the conditions it needs and why it exists, so you can disagree with it.

  • Mooneye in clearer river habitat retain a stronger conventional drift/surface insect identity than goldeye.

    When

    Flowing water · Run, Pool tail, Current break, Seam · Aquatic insects, Emerging insects, Terrestrial insects

    Moves up

    Dead drift, Surface drift, Swing, Cross-current retrieve

    Reviewed 2026-08-27

  • Observed fish forage can move mooneye toward mobile prey mechanics without importing goldeye's turbidity assumptions.

    When

    Current break, Deep pool, Drop-off, Shallow flat · Small forage fish

    Moves up

    Cross-current retrieve, Horizontal retrieve, Stop-and-go, Swing

    Reviewed 2026-08-27

Where every sentence came from

Sources

Reviewed 2026-08-27, next review 2026-11-27. Each entry says which part of the page leans on it, so you can check the claim you care about rather than the whole list.

  1. Agency

    Ontario mooneye species profile

    Used for habitat, thermal band and presentation families; identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-27.

  2. Agency

    Minnesota DNR cisco / lake whitefish / mooneye identification

    Used for identification. Read 2026-08-30, next check 2026-11-16.

  3. Agency

    Minnesota DNR mooneye notes (Rainy River mayfly window as documented feeding class)

    Used for behaviour. Read 2026-08-30, next check 2026-12-01.

  4. Peer reviewed

    Hoover juvenile goldeye identification (goldeye vs mooneye key)

    Used for identification. Read 2026-08-30, next check 2026-11-16.

  5. Synthesis

    Hiodontidae life-history synthesis

    Used for habitat, thermal band and presentation families; forage; season. Read 2026-08-30, next check 2026-11-27.

A source with no link predates the rule that one has to carry a URL. It is still a real citation and still checkable; it just takes a search rather than a click, and that is worth knowing before you rely on it.