Other freshwater · Freshwater
Longnose sucker
Catostomus catostomus
Northern coldwater sucker of clear streams and lakes, with broad circumpolar North American distribution and stronger cold/clean-substrate association than white sucker.
Also called long-nosed sucker.
- Flowing water
- Stillwater
- Ordinary target
- 4 of 4 overlays reviewed
- Reviewed 2026-08-27
Photograph · reviewed 2026-08-27
High-resolution USFWS longnose sucker photograph; kept visually and biologically distinct from white sucker despite possible co-occurrence/hybridization.
U.S. Fish and Wildlife Service · U.S. Fish and Wildlife Service · Public Domain — U.S. federal government work Source
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 Longnose sucker there are 22 of them.
Named by a reviewer
20Somebody looked for this and wrote down that they did not find it.
- Behaviour
Nobody has sourced:
- adult diel activity pattern — no source reached established one, and this is the main reason the record is partial
- non-spawning social structure (shoal vs. dispersed)
- winter habitat and overwintering behaviour
- cold-front / barometric response
- water-level and flow-change response
- angling-pressure response
- predator avoidance and territoriality — not described in any source reached
- Identification
Nobody has sourced:
- regional / vernacular names — no agency source reached supplied a list
- regional colour variation
- an exact upper bound on the lateral-line scale count; the agency sources reached give only 'more than 85'
- a field character for separating longnose × white and longnose × largescale hybrids from either parent
- a sourced field character separating longnose sucker from bridgelip sucker where the two overlap in the Columbia basin
- Forage
Nobody has sourced:
- the agency accounts also document mollusks (snails and fingernail clams), algae and plant material, and fish eggs, none of which the catalog carries as forage classes for this species; the catalog classes have been kept and the discrepancy recorded rather than resolved
- a quantified gut-content study for this species; the diet statements reached are qualitative lists
- season-by-season diet shifts outside the documented autumn egg predation
- prey-size shifts with growth
- Season
Nobody has sourced:
- winter entry omitted — no sourced description of overwintering habitat or activity
- light sensitivity / diel pattern for adults
- stillwater seasonal structure beyond the general statement that lake fish use deep cold water
- the catalog's still-water holding classes for this species (rocky shoreline, drop-off, inlet, basin) are not individually documented in any source reached; only deep cold lake water and inlet/outlet spawning streams are
Absent from the record
2No 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 Longnose sucker was found that a review would accept. The reading runs without one rather than borrowing a number from a related fish.
- 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- Riffle-to-run transition
- Run
- Pool tail
- Current break
- Deep pool
Stillwater
4 reviewed holding classes- Rocky shoreline
- Drop-off
- Inlet
- Basin
DepthBenthic in both lakes and streams, shifting among riffle/run feeding areas, pool refuge, and lake depth/substrate edges.
Moving waterUses cold clear streams and moderate current more readily than white sucker while remaining strongly bottom-oriented.
LightLight is secondary to substrate, current, and benthic food; clear bright water can reinforce slightly deeper use.
Thermal band
Temperature
No reviewed temperature band
Nobody publishes a preferred or active temperature range for Longnose sucker 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
Recorded conservatively. The sources reviewed describe spawning migrations into small tributaries as common and describe adults sharing the same pool and run habitat, but none of them resolves whether non-spawning fish shoal or disperse. Spawning aggregation is conservation context only and is not located here.
A benthic invertivore working the bottom with large papillose lips and suction. Alaska's account states plainly that the species feeds primarily on the bottom of streams and lakes. Prey is taken off and out of the substrate rather than intercepted in the drift.
Recorded as a non-claim. No agency or peer-reviewed source reviewed here resolves an adult diel activity pattern for longnose sucker. The only diel-relevant item reached is larval: Pennsylvania reports that most larvae migrate downstream at night in high, turbid water. 'Mixed' is entered because the field is required, and the gap is listed rather than filled with a guess.
Seasonal activitySpring is the resolved season. Spawning migrations from lakes into tributary rivers and streams are common, running April through early July in Montana with a May peak in Missouri River populations, March to May in the British Columbia summary, and May to June elsewhere. British Columbia documents out-migration from spawning streams in mid to late June. Autumn and winter activity is not resolved by the sources reviewed.
Temperature-driven behaviourA genuinely cold-adapted sucker, and the one whose catalog band is best corroborated. The Ontario database gives a preferred range of 8–17 °C and an upper lethal limit of 27 °C; Pennsylvania states the species cannot tolerate warm water and gives an upper lethal limit of 26.5 °C. The catalog's 48–62 °F band (about 9–17 °C) sits squarely inside the reported preferendum. Montana notes it occasionally tolerates moderately warm and turbid water but is most abundant in clear, cold streams.
Depth movementThe Ontario database gives clear, cold, deep water to 55 m in lakes and tributary streams. In streams Pennsylvania places adults in deeper pools and slower runs and young-of-year in lower, more sluggish sections. British Columbia adds that at the southern edge of its range the species is restricted to the deep, cool portions of lakes.
Facing the currentPennsylvania places stream fish most frequently in deeper pools and slower runs, usually below riffles or torrents rather than in them. British Columbia places spawning fish in run habitat over gravel-cobble. This is a fish of moderate flow adjacent to fast water, not of the fast water itself.
ClarityAssociated with clear, cold water across the agency accounts, with Montana allowing occasional tolerance of moderately warm and turbid conditions. Pennsylvania ties it to clean gravel and cobble with well-oxygenated conditions.
CoverPennsylvania names boulder-rubble substrate and submerged coarse woody debris as the structure adults use in deeper pools and slower runs. This is the only cover statement any source reviewed provides.
Spawning (conservation context)Spring spawner over loose gravel in riffle and run habitat, reached by migrations out of lakes and larger rivers into small tributaries. Montana gives 54–59 °F from April through early July; Pennsylvania gives primary spawning at 10–15 °C; the Ontario database gives 5–15 °C; British Columbia gives initiation near 5 °C in inlet or outlet streams, ceasing near 15 °C, at spawning depths of 0.1–0.6 m. It is an open-substratum, non-guarding spawner. Fecundity is reported at 14,000–35,000 eggs (Pennsylvania), 10,270–89,000 (Ontario) and up to 60,000 (Alaska); eggs hatch in about two weeks, or seven days above 10 °C. Spawning substrate and any spawning-period concentration are excluded from target guidance.
Where the general rule stops
- Longnose sucker diet also includes algae; this model represents the animal-food component that maps to presentation mechanics.
- Do not collapse longnose and white sucker simply because both occur in the same water and can hybridize.
What it can eat
Forage
- Aquatic insects
- Worms / annelids
- Crustaceans
A bottom-feeding invertivore. Montana names considerable algae, midge larvae and most aquatic invertebrates; Pennsylvania names crustaceans, insect larvae, fingernail clams, snails, cladocerans and plants; Massachusetts names benthic invertebrates specifically including Gammarus amphipods, Daphnia and a variety of insect larvae as well as algae; Alaska names insects, mollusks, snails and crustaceans with occasional aquatic plants, algae and fish eggs. British Columbia describes it as a benthic forager on insects, amphipods and molluscs. Capacity is not a current hatch.
- Feeding style
- Opportunistic
- Feeding zone
- Benthic
Through the year
- Fall
- Egg predation is documented as a real capacity rather than an inference: Nester and Poe recorded intense predation on lake whitefish eggs by longnose suckers on whitefish spawning grounds in November. That is a capacity statement about what the species will eat when eggs are on the bottom in front of it, not a prediction that eggs are present in any given water.
By life stage
- Young of year
- British Columbia reports young-of-year taking smaller prey including plankton and algae.
- Adult
- Benthic invertivore: midge and other insect larvae, amphipods and other crustaceans, small mollusks and worms taken off and within the substrate, with a substantial algal fraction.
Ontogenetic shiftFrom plankton- and algae-scale prey in the first year to bottom-worked insect larvae, crustaceans and mollusks as adults.
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
Spring
- Where they sit
- Riffle-to-run and run over loose gravel and cobble in the small tributaries adults move into, and the pool tails and current breaks adjacent to that water. Inlet and outlet streams of lakes are the route in British Columbia's account.
- Movement
- Migration out of lakes and larger rivers into small tributaries, then out-migration in mid to late June.
- Feeding
- Bottom-worked insect larvae and crustaceans; feeding is a substrate activity throughout.
- Temperature
- Spawning from about 5 °C, primary spawning at 10–15 °C, ceasing near 15 °C; Montana gives 54–59 °F from April through early July with a May peak.
What that changesBottom-contact drift and tight-line drift keep an offering on the substrate where this species feeds, and stationary bait is the other reviewed flowing family that matches a downward-facing benthic invertivore. In stillwater, bottom contact and slow drag. Surface and mid-column families do not match the mouth.
What would count against it
- treating the tributary migration as a location cue
- reading a spawning aggregation as holding water
Spring spawner. Spawning substrate and any spawning-period concentration are excluded from target guidance.
Summer
- Where they sit
- Deep pools and slower runs below riffles and torrents, over boulder-rubble substrate or submerged coarse woody debris; in lakes, the deep, cold water the species is confined to at the southern edge of its range.
- Depth
- Deep. The Ontario database gives lake use to 55 m; stream adults sit in the deeper pools while young-of-year hold in lower, more sluggish sections.
- Temperature
- Preferred 8–17 °C against an upper lethal limit of 26.5–27 °C. The warm edge is the real constraint and it is close: this species cannot tolerate warm water, and Montana lists warming as its principal threat.
- Current
- Beside fast water rather than in it — below riffles, in slower runs and deeper pools.
- Cover
- Boulder-rubble substrate and submerged coarse woody debris.
What that changesBottom-contact drift and tight-line drift in flowing water, stationary bait where the substrate allows; bottom contact and slow drag in stillwater.
What would count against it
- fishing it as a mid-column or surface feeder
- forcing fast riffle water — the accounts place adults below and beside it, not in it
- assuming it holds where summer temperatures approach the warm edge
Fall
- Where they sit
- The same deep pools, slower runs and deep lake water as summer; no autumn habitat shift is documented in the sources reviewed.
- Forage
- Documented capacity to feed heavily on fish eggs where they are present on the bottom. That is capacity, not a declared event, and the presence of eggs still has to come from an observation.
What that changesBottom-contact drift, tight-line drift and stationary bait in flowing water; bottom contact and slow drag in stillwater. The mechanics do not change because the calendar does.
What would count against it
- importing a fall-spawning pattern from salmonids — this is a spring spawner
- assuming an egg event from the calendar alone
Spawning · Spring, Early summer
Spawns April into early July over loose gravel riffles; Montana reports spawning around 54–59°F. Spawning riffles are excluded from target guidance.
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
- More than 85 scales in the complete lateral line (Connecticut DEEP, Massachusetts), against 55–85 in white sucker. Massachusetts adds that the lateral-line pores are visible in longnose and not in white sucker. Montana gives more than 15 scale rows above the lateral line.
- Snout long and pointed, noticeably overhanging the mouth; the rear corner of the mouth reaches back beyond the nostrils (Connecticut DEEP, Peace River key).
- Deep cleft between the lower lips; Massachusetts describes the lower lips as looking like two square flaps, where white sucker's taper.
- Lips large and covered with papillae, used for suction feeding; no jaw teeth, pharyngeal teeth working against a cartilage pad.
- Dorsal fin of 9–12 rays (Montana), given as 10 by Connecticut DEEP.
- Scales small enough to be barely visible on juveniles (Peace River key) — the opposite of largescale sucker, whose scales are distinct even in young fish.
- Young fish usually carry small dark spots (Connecticut DEEP).
- Average adult length
- Adults typically 30.5–45.7 cm total length (Ontario database); 300–400 mm in New England (Massachusetts). Alaska's account puts most fish under 23 in.
- Common angling size
- Most fish encountered run about 12–16 in; Montana notes longnose sucker is among the fish most frequently caught by anglers in the state.
- Typical weight
- 0.3–1.0 kg for typical adults (Ontario database). Montana gives Montana fish up to 5 lb.
- Maximum documented
- To about 64 cm and 3.31 kg (Ontario database). Pennsylvania cites the largest known individual as a 642 mm fork length, 3.31 kg female of 19 years from Great Slave Lake. Alaska and Connecticut both give lengths to about 25 in.
- Longevity
- The Ontario database gives 19–28 years. Males mature at 4–6 years and females at 5–7 (Ontario); Montana gives males at 4 and females at 5, and Alaska reports maturity as early as 2–3 years in some populations.
What it gets confused with
- White sucker
- Count the lateral line. Longnose carries more than 85 scales, white sucker 55–85 and usually 60–75; longnose's lateral-line pores are visible and white sucker's are not. Longnose's snout is long and pointed and noticeably overhangs the mouth, with the rear of the mouth reaching past the nostrils; white sucker's is short and rounded, barely projecting, with the mouth not reaching the nostrils. The lower-lip cleft is deep in longnose and a narrow inverted 'V' in white sucker. The two hybridize — Montana documents it at several locations and British Columbia reports it too — so intermediate fish occur and some specimens will not key cleanly.
- Largescale sucker
- Scale size does the work, and it works even on juveniles: longnose scales are small and barely visible on young fish, largescale scales are large and distinct at every size (62–80 in the lateral line). The snouts differ too — longnose's is long and pointed and noticeably overhangs the mouth, largescale's is short and rounded and barely does — and the lower-lip cleft is deep in longnose against a broad, shallow inverted 'V' in largescale. The dorsal fin is a further check: 9–12 rays on a short base in longnose, 13–15 on an elongated base in largescale. British Columbia reports the two may hybridize, and notes morphological characters can overlap in some specimens, so treat an intermediate fish as unresolved rather than forcing it into a record.
- Mountain sucker (Catostomus platyrhynchus)
- A size and marking cut rather than a lip cut in the sources reached: mountain sucker averages only 127–152 mm total length with a largest recorded specimen of 232 mm, and carries a dark green-to-black lateral band and/or five dorsal blotches of fine black pigment on the sides. Longnose sucker reaches several times that length and adults are unmarked.
- Shorthead redhorse
- Shorthead redhorse has large, evenly sized scales, plicate (folded) lower lips rather than papillose ones, a very short head, and a red caudal fin. Longnose sucker is fine-scaled, long-snouted, papillose-lipped, and has no red tail outside of spawning colour on the flank.
What follows from all of that
Presentation families
Flowing water
Bottom-contact drift
Tick or crawl a food form along the substrate through a feeding lane without snagging constantly.
- feel the bottom
- short hops
- reset after hang
- weight just enough
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
Stationary bait
Hold a scent or food form in one feeding station and wait for a fish to move to it.
- anchor the presentation
- keep bait in the pocket
- detect takes without sweeping
- refresh often
What it asks of the tackle
- Depth control
- High
- Sensitivity
- Moderate
- Casting distance
- Short
- Weight range
- 1/4–1 oz
- Cover resistance
- High
- Line visibility
- Moderate
- Retie frequency
- High
Pulse / jig
Lift and drop a compact bait so it occupies a pocket, seam, or head without leaving the water column.
- short lift
- controlled drop
- stay in the pocket
- repeat on the same piece
What it asks of the tackle
- Depth control
- High
- Sensitivity
- High
- Casting distance
- Short to moderate
- Weight range
- 1/8–3/8 oz
- Cover resistance
- Moderate
- Line visibility
- Low
- Retie frequency
- High
Stillwater
Bottom contact
Keep a bait on or just above the substrate along a break, flat, or inside a weed edge.
- feel bottom
- drag or hop
- pause on the break
- stay in contact
What it asks of the tackle
- Depth control
- High
- Sensitivity
- High
- Casting distance
- Moderate
- Weight range
- 1/8–1/2 oz
- Cover resistance
- High
- Line visibility
- Low
- Retie frequency
- High
Slow drag
Move a bait along the bottom slowly enough that it stays in the feeding layer of inactive fish.
- continuous contact
- very slow travel
- pause at changes in bottom
- do not hop out of the zone
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
Live / natural bait suspension
Present a natural food form with enough life or scent to hold in a station without looking mechanical.
- keep it alive or fresh
- match the holding depth
- minimize hardware bulk
- detect without pulling it away
What it asks of the tackle
- Depth control
- High
- Sensitivity
- High
- Casting distance
- Short to moderate
- Weight range
- As light as conditions allow
- Cover resistance
- Moderate
- Line visibility
- Low
- Retie frequency
- High
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.
Longnose sucker retain a colder, clearer, more current-tolerant benthic identity than white sucker.
When
Flowing water · Riffle-to-run transition, Run, Pool tail, Current break · Aquatic insects, Worms / annelids, Crustaceans
Moves up
Bottom-contact drift, Stationary bait, Pulse / jig
Reviewed 2026-08-27
In lakes, longnose sucker remain substrate feeders and should not be converted into pelagic whitefish logic.
When
Stillwater · Rocky shoreline, Drop-off, Inlet, Basin
Moves up
Bottom contact, Slow drag, Live / natural bait suspension
Reviewed 2026-08-27
Where every sentence came from
Sources
Agency
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-19.
Agency
Alaska Department of Fish and Game, Wildlife Notebook Series — Longnose Sucker
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-19.
Agency
Pennsylvania Fish and Boat Commission — Species Action Plan: Longnose Sucker
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-19.
Agency
Used for identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-19.
Agency
Connecticut DEEP — Freshwater Fishes of Connecticut: Longnose Sucker
Used for identification; behaviour; season. Read 2026-08-30, next check 2026-11-19.
Agency
Massachusetts Division of Fisheries and Wildlife — Longnose Sucker
Used for identification; forage. Read 2026-08-30, next check 2026-11-19.
Agency
Montana Field Guide Longnose Sucker species account
Used for habitat, thermal band and presentation families. Read 2026-08-27, next check 2026-11-27.
Agency
Used for identification. Read 2026-08-30, next check 2026-11-19.
Peer reviewed
Used for forage; season. Read 2026-08-30, next check 2026-11-28.
Synthesis
Ontario Freshwater Fishes Life History Database — Longnose Sucker record
Used for identification; behaviour; season. Read 2026-08-30, next check 2026-11-19.
Synthesis
Used for identification. Read 2026-08-30, next check 2026-11-19.
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.