Other freshwater · Freshwater
Paddlefish
Polyodon spathula
Ancient native filter-feeding fish of the Mississippi River basin, dependent on large connected rivers and reservoirs.
Also called spoonbill, spoonbill cat.
- Flowing water
- Stillwater
- Regulated context
- 4 of 4 overlays reviewed
- Reviewed 2026-08-27
Before you target this fish
Regulated context — check the rules for the exact water
Paddlefish fisheries often use special seasons, permits, and legal methods. This record provides biology and positioning context but intentionally gives no presentation or capture-method guidance.
Where this applies Mississippi-basin states and managed reservoirs; special seasons, permits, and legal methods are common.
The reviewed context, unedited
Regulated biological context. Paddlefish are filter feeders; the app must not manufacture lure-style presentation guidance or convert migration timing into aggregation instructions.
Rules for this fish change at a state line and sometimes inside one. Check the ones that apply to the exact water you are standing on before you act on anything here — this record is biology, not permission.
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.
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 Paddlefish there are 22 of them.
Named by a reviewer
16Somebody looked for this and wrote down that they did not find it.
- Behaviour
Nobody has sourced:
- diel activity pattern — no source reached established one, a main reason this record is partial
- an adult thermal preference or avoidance study
- clarity, cold-front and angling-pressure responses
- territoriality and aggression — no source reached describes either, consistent with a non-territorial open-water filter feeder but not positively established
- the movement study reached tracked five fish in one river system over eleven months and should not be generalised
- Identification
Nobody has sourced:
- regional / vernacular names — no agency source reached supplied a list
- a typical (as opposed to maximum) adult weight
- sexual dimorphism outside of age at maturity
- coloration variation between river and reservoir populations
- Forage
Nobody has sourced:
- seasonal diet emphasis and how filtration rate varies with plankton density
- quantitative diet composition by mass for wild adults
- how much of the diet the reported aquatic insects and occasional small fish actually represent
- Season
Nobody has sourced:
- fall habitat use specifically — the fall entry is interpolated between the sourced spring peak and the sourced winter minimum in movement, which is the main reason this record is partial
- light sensitivity and diel depth shifts
- how the 2–12 m congregation band varies between river and reservoir populations
- tributary-mouth and tailwater use, which the catalog lists as river holding but which the sources reached do not document outside the spawning-migration context
Absent from the record
6No reviewer wrote a gap here. The field is simply empty, which is its own answer.
- Presentation
No presentation family is reviewed for Paddlefish in flowing water. The record documents the fish there; it does not yet say how to fish for it there.
No presentation family is reviewed for Paddlefish in stillwater. The record documents the fish there; it does not yet say how to fish for it there.
No species-specific weighting rule is reviewed for Paddlefish. Its ranking comes from the shared model — season, temperature, water type, holding and forage — with nothing added for this fish in particular.
- Water temperature
No agency or peer-reviewed temperature band for Paddlefish 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
Flowing water
5 reviewed holding classes- Deep pool
- Run
- Current break
- Tailwater
- Tributary mouth
Stillwater
4 reviewed holding classes- Suspended / open water
- Basin
- Inlet
- Drop-off
DepthPelagic to mid-depth rather than structure-bound; depth follows flow, plankton distribution, and seasonal movement.
Moving waterUses large deep slow-to-moderate river corridors and reservoir open water; movement can track discharge and plankton-rich water masses.
LightLight is secondary to plankton and hydrology, though vertical distribution can shift through the day.
Thermal band
Temperature
No reviewed temperature band
Nobody publishes a preferred or active temperature range for Paddlefish 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
Missouri Department of Conservation describes paddlefish in the open water of large rivers, swimming continuously and holding no fixed home range. The New York status assessment describes fish congregating within a preferred depth band. Neither source describes coordinated schooling, and the telemetry work reached found individuals ranging over an entire navigation pool with most stays at a location lasting under three to six days. Treat 'loose_aggregation' as shared use of a depth band and a food resource, not as a shoal.
An obligate ram suspension feeder as an adult. The fish swims slowly with its mouth wide open and strains zooplankton from the water with numerous long, fine gill rakers. Haines and Sanderson (2017) showed the mechanism is not simple sieving but vortical cross-step filtration, in which flow patterns organised by the branchial arches carry particles to the posterior margins of the gill slots; their model swam at a mean 0.75 total lengths per second, and swimming kinematics sharply reduced fouling of the filter (23.5% mesh coverage while swimming versus 86.6% stationary). Young fish under a year old use small teeth to pick individual zooplankton before switching to gill-raker filtration. The rostrum functions as an electrosensory organ for detecting plankton. There is no strike, no pursuit and no prey-capture event of the kind a presentation could imitate.
Not resolved. No source reached established a diel activity pattern for paddlefish; 'mixed' is entered as the least-committing value rather than as a finding. See gaps.
Seasonal activityMovement rates are highest in the spring spawning period. Welsh et al. (2024), tracking paddlefish in the Ohio and Kanawha rivers, recorded most movement in April and May and reduced movement in colder months, with no movement observed in February. Two of five tagged fish used an entire navigation pool over an eleven-month study; 60% of stays at a receiver lasted under three days and 78% under six.
Temperature-driven behaviourThe best-sourced thermal numbers are reproductive: the New York status assessment gives spawning triggered at 50–65°F, and notes current New York spring temperatures may be too cold for paddlefish spawning. The catalog preferred band of 58–74°F is not contradicted by that, but no adult thermal-preference or avoidance study was found in the sources reached, so the band is not corroborated here.
Depth movementThe New York status assessment gives a preference for depths greater than 1.5 m, with fish congregating at 2–12 m and an optimum of 3–6 m, and relocation to deeper water (greater than 3 m) in winter. Missouri Department of Conservation describes fish in open water of large rivers swimming near the surface.
Water levelSubstantial rises in water level, together with higher flows, rising temperature and changing photoperiod, are the documented spawning cues. This is a reproductive trigger, not a feeding response.
Open waterThis is the species' normal condition: open water of large rivers, reservoirs and deep slow river sections, swimming continuously with no fixed home range. USGS gives large, deep, slow-moving rivers, lakes and reservoirs as the habitat.
Spawning (conservation context)Spring spawner. The New York status assessment gives spawning from late spring through early summer (April–June), triggered by water temperatures of 50–65°F, higher flows, substantial rises in water level and changing photoperiod, with migrations of 50–200 miles to reach flooded, fast-flowing tributary reaches with clean gravel. Missouri Department of Conservation gives late spring at high water on silt-free gravel bars, with eggs needing shallow water or exposure at normal levels and larvae drifting downstream to deeper pools. Spawning areas, staging concentrations and migration bottlenecks are conservation context and are neither located nor described in this record. Dams that block spawning migrations are a primary cause of decline, and many impoundment populations do not reproduce naturally and are maintained by stocking.
Where the general rule stops
- Paddlefish are filter feeders; lure-style forage matching is not biologically appropriate.
- Do not convert migration timing into snagging or aggregation instructions.
What it can eat
Forage
- Zooplankton
Paddlefish are filter feeders and effectively single-resource specialists on zooplankton. USGS describes them straining zooplankton from the water with numerous large, fine gill rakers; Missouri Department of Conservation describes them swimming slowly with mouths wide open, collecting tiny crustaceans and insects; North Dakota Game and Fish gives zooplankton as the main food with aquatic insects and occasional small fish also taken. Fish under one year old pick individual zooplankton with small teeth, then switch to gill-raker filtration. The rostrum is an electrosensory organ used to detect plankton. The mechanical consequence matters more than the taxon list: there is no strike and no prey-capture event. North Dakota Game and Fish states that paddlefish will not take large bait, which is why harvest, where legal, is by snagging rather than by any presentation. Capacity is not a current forage event.
- Feeding style
- Specialized
- Feeding zone
- Pelagic
By life stage
- Young of year
- Selective particulate feeding — individual zooplankton picked with small teeth during the first year.
- Adult
- Ram suspension filtration of zooplankton, with aquatic insects and occasional small fish also reported.
Ontogenetic shiftFrom selective particulate feeding with teeth in the first year to obligate gill-raker filter feeding thereafter; the teeth are absent in adults.
Diet capacity is not proof that a forage event is occurring, and for this species the rule takes an additional form: a zooplankton diet is not a forage cue an angler can act on. Observed current forage still comes from a user observation or Hatch Match, and no observation of plankton density converts into presentation guidance for a filter feeder.
Through the year
Season
Winter
- Where they sit
- Deep pool and basin; suspended in open water. The New York status assessment gives relocation to water deeper than 3 m in winter.
- Depth
- Deeper than the 2–12 m general band, moving below about 3 m.
- Movement
- Reduced. Welsh et al. (2024) observed no movement in February and reduced movement generally in colder months.
What would count against it
- reading a depth band as target guidance for a species not taken on a presentation
Not a presentation-caught species. Where a snagging fishery exists at all it is bounded by jurisdiction-specific season dates, permits and quotas; nothing in this entry implies an open season.
Spring
- Where they sit
- Open-water river habitat; the spawning migration is under way through this period and is treated as conservation context only (see the conservation note).
- Movement
- Highest of the year. Welsh et al. (2024) recorded most movement in April and May, with tagged fish frequenting the upper section of a navigation pool.
- Temperature
- Spawning is triggered at 50–65°F together with higher flows, substantial water-level rises and changing photoperiod.
What would count against it
- treating the spawning migration as an opportunity
- assuming natural reproduction occurs in an impoundment population
Spring is the spawning period, and the New York assessment records migrations of 50–200 miles to reach suitable reaches. Spawning areas, staging concentrations and migration bottlenecks are not located or described in this record. Dams that block these migrations are a primary cause of decline, and many impoundment populations do not reproduce naturally and persist only through stocking. No presentation implication is given, in this or any season.
Summer
- Where they sit
- Open water of large rivers, reservoirs and deep slow river sections — suspended open water, basin, deep pool, and current-break or tailwater in flowing systems.
- Depth
- Deeper than 1.5 m as a floor, congregating at 2–12 m with an optimum of 3–6 m; Missouri Department of Conservation also describes fish swimming near the surface in open river water.
- Forage
- Zooplankton, filtered continuously rather than taken in discrete feeding events. Water rich in zooplankton is the habitat requirement.
What would count against it
- converting a plankton concentration into a presentation cue
- treating the surface-swimming description as a surface-feeding behaviour
Not a presentation-caught species. The continuous ram-filtration feeding mode means there is no strike to provoke; a zooplankton food base is a habitat fact, not a forage cue.
Fall
- Where they sit
- Open-water river and reservoir habitat continues; movement begins to slow ahead of winter.
- Movement
- Declining from the spring peak toward the winter minimum.
What would count against it
- assuming an open season — jurisdictional rules govern
Not a presentation-caught species; jurisdiction-specific rules govern any harvest. Zebra mussels competing for plankton are noted by Missouri Department of Conservation as an added pressure in infested waters.
Spawning · Spring, Early summer
Spring high-water cues trigger long migrations to silt-free gravel spawning habitat; aggregation routes are not targeting outputs.
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
What to look at
- The paddle-shaped rostrum ahead of the mouth is unmistakable — no other North American freshwater fish has one. USGS gives it as up to one third of total body length.
- Mouth is very large and toothless in adults and set far back beneath the head.
- Eyes are small and directed downward.
- A fleshy, pointed flap trails from the gill cover.
- No scales except a patch on the tail.
- Gill rakers are numerous, long and fine — the filtering apparatus, visible when the mouth is opened.
- Average adult length
- USGS gives about 150 cm (roughly 59 in) as common. Missouri Department of Conservation gives 17-year-old fish at about 60 in and first-year fish at 10–14 in.
- Common angling size
- Set by regulation, not by biology, and in most waters the fish is not taken on a presentation at all. North Dakota Game and Fish states plainly that paddlefish will not take large bait, which is why anglers seeking to harvest one must snag. Where a snagging fishery exists it runs under jurisdiction-specific permits, quotas, season dates and length limits — Missouri, for example, opens a defined spring snagging season. Any size expectation must come from the local rule set.
- Typical weight
- The agency sources reached give maxima rather than a typical weight. Missouri Department of Conservation gives over 160 lb for the largest fish; no typical adult weight was found.
- Maximum documented
- Missouri Department of Conservation gives about 7 ft and over 160 lb. USGS gives a maximum total length of 221 cm.
- Longevity
- Missouri Department of Conservation gives a lifespan of more than 30 years. The New York species status assessment gives about 15 years typically, with individuals documented at 30–50 years; males mature at 7–9 years and females at 9–12, with males spawning annually and females every two to seven years.
What it gets confused with
- Lake sturgeon
- Lake sturgeon have a conical snout, five rows of bony scutes and four barbels ahead of a small protrusible mouth. Paddlefish have a paddle rostrum, no scutes and a very large toothless mouth. Both have shark-like heterocercal tails, which is the character that causes the confusion.
- Shovelnose sturgeon
- Listed by Missouri Department of Conservation as a paddlefish look-alike in large-river systems. It is a scute-bearing sturgeon with barbels and a flattened shovel snout, not a paddle rostrum.
- Longnose gar
- Also listed by Missouri Department of Conservation as a look-alike. The gar's long snout is a toothed beak-like jaw, not a flat paddle, and the gar is heavily armoured with ganoid scales where the paddlefish is essentially scaleless.
What follows from all of that
Presentation families
Flowing water
The record documents Paddlefish in flowing water but has no reviewed presentation family for it. Presence and a method are different claims and only the first one is made here.
Stillwater
The record documents Paddlefish in stillwater but has no reviewed presentation family for it. Presence and a method are different claims and only the first one is made here.
What moves them for this fish
No species-specific rule is reviewed for Paddlefish. Its ranking comes from the shared model — season, temperature, water type, holding water, forage — with nothing added for this fish in particular. That is a gap, not a claim that nothing is special about it.
Where every sentence came from
Sources
Agency
Missouri Department of Conservation field guide: Paddlefish
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-25.
Agency
USGS Nonindigenous Aquatic Species species profile: Paddlefish (Polyodon spathula)
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-25.
Agency
North Dakota Game and Fish Department: what do paddlefish eat, and how do they do it?
Used for identification; behaviour; forage. Read 2026-08-30, next check 2026-11-25.
Agency
New York State Department of Environmental Conservation, Species Status Assessment: Paddlefish
Used for identification; behaviour; season. Read 2026-08-30, next check 2026-11-25.
Agency
U.S. Fish & Wildlife Service paddlefish species profile
Used for habitat, thermal band and presentation families. Read 2026-08-27, next check 2026-11-27.
Agency
USFWS paddlefish conservation and hatchery literature
Used for habitat, thermal band and presentation families. Read 2026-08-27, next check 2026-11-27.
Agency
Used for season. Read 2026-08-30, next check 2026-11-16.
Peer reviewed
Used for behaviour; forage. Read 2026-08-30, next check 2026-12-02.
Peer reviewed
Used for behaviour; season. Read 2026-08-30, next check 2026-12-02.
Peer reviewed
Paddlefish movement and filter-feeding ecology literature
Used for habitat, thermal band and presentation families. Read 2026-08-27, 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.