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Brown Trout

Salmo trutta

Fish · family Salmonidae · order Salmoniformes

  1. G1
    Critically imperiled
  2. G2
    Imperiled
  3. G3
    Vulnerable
  4. G4
    Apparently secure
  5. G5
    Secure

NatureServe global rank G5: secure[2].

Updated October 30, 2026. Published by Humblebee.

Brown Trout
Photo: Duane Raver, U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons.
Endangered Species Act
Not listed[1]
NatureServe global rank
G5 Secure[2]
Longest recorded life
38 years[3]

The Brown Trout (Salmo trutta) is a fish in the salmon and trout family, Salmonidae[4]. NatureServe ranks it G5 (Secure) worldwide, and in the United States it is an introduced species in many states[2][5].

Conservation status

NatureServe gives the Brown Trout a global rank of G5, which means Secure[2]. The IUCN Red List category recorded by NatureServe is Least concern[6]. It is not listed as endangered or threatened under the US Endangered Species Act in USFWS data checked on 2026-10-30[1]. In the states where NatureServe records it, the state rank is SNA, which marks species that are not native there[7].

Status Value
Endangered Species Act[1] Not listed
NatureServe global rank[2] G5 (Secure)
IUCN Red List (via NatureServe)[6] Least concern
USGS nonindigenous aquatic species[8] Listed as exotic in parts of the US

Where Brown Trout lives

USGS lists the Brown Trout as a nonindigenous (exotic) aquatic species in parts of the United States[8]. NatureServe records it as introduced, not native, in 43 places, including Alabama, California, Colorado, Michigan, Montana, New York, Pennsylvania, Utah and Wyoming, and the District of Columbia[5][7]. The facts here do not list any US state where it is native. Online reports of the fish are most numerous for Pennsylvania, New Jersey, Wyoming, New York and New Mexico, but that follows where people look and report, not how many fish live there[9].

Alaska: not recordedAKMaine: introduced, state rank SNAMEWisconsin: introduced, state rank SNAWIVermont: introduced, state rank SNAVTNew Hampshire: introduced, state rank SNANHWashington: introduced, state rank SNAWAIdaho: introduced, state rank SNAIDMontana: introduced, state rank SNAMTNorth Dakota: introduced, state rank SNANDMinnesota: introduced, state rank SNAMNIllinois: introduced, state rank SNAILMichigan: introduced, state rank SNAMINew York: introduced, state rank SNANYMassachusetts: introduced, state rank SNAMAOregon: introduced, state rank SNAORNevada: introduced, state rank SNANVWyoming: introduced, state rank SNAWYSouth Dakota: introduced, state rank SNASDIowa: introduced, state rank SNAIAIndiana: introduced, state rank SNAINOhio: introduced, state rank SNAOHPennsylvania: introduced, state rank SNAPANew Jersey: introduced, state rank SNANJConnecticut: introduced, state rank SNACTRhode Island: introduced, state rank SNARICalifornia: introduced, state rank SNACAUtah: introduced, state rank SNAUTColorado: introduced, state rank SNACONebraska: introduced, state rank SNANEMissouri: introduced, state rank SNAMOKentucky: introduced, state rank SNAKYWest Virginia: introduced, state rank SNAWVVirginia: introduced, state rank SNAVAMaryland: introduced, state rank SNAMDDelaware: introduced, state rank SNADEArizona: introduced, state rank SNAAZNew Mexico: introduced, state rank SNANMKansas: not recordedKSArkansas: introduced, state rank SNAARTennessee: introduced, state rank SNATNNorth Carolina: introduced, state rank SNANCSouth Carolina: not recordedSCDistrict of Columbia: introduced, state rank SNADCOklahoma: introduced, state rank SNAOKLouisiana: not recordedLAMississippi: not recordedMSAlabama: introduced, state rank SNAALGeorgia: introduced, state rank SNAGAHawaii: not recordedHITexas: not recordedTXFlorida: not recordedFLPuerto Rico: not recordedPR
State presence as recorded by NatureServe[7].
Show state ranks (43 states)
StateRankMeaning
AlabamaSNANot Applicable
ArizonaSNANot Applicable
ArkansasSNANot Applicable
CaliforniaSNANot Applicable
ColoradoSNANot Applicable
ConnecticutSNANot Applicable
DelawareSNANot Applicable
District of ColumbiaSNANot Applicable
GeorgiaSNANot Applicable
IdahoSNANot Applicable
IllinoisSNANot Applicable
IndianaSNANot Applicable
IowaSNANot Applicable
KentuckySNANot Applicable
MaineSNANot Applicable
MarylandSNANot Applicable
MassachusettsSNANot Applicable
MichiganSNANot Applicable
MinnesotaSNANot Applicable
MissouriSNANot Applicable
MontanaSNANot Applicable
NebraskaSNANot Applicable
NevadaSNANot Applicable
New HampshireSNANot Applicable
New JerseySNANot Applicable
New MexicoSNANot Applicable
New YorkSNANot Applicable
North CarolinaSNANot Applicable
North DakotaSNANot Applicable
OhioSNANot Applicable
OklahomaSNANot Applicable
OregonSNANot Applicable
PennsylvaniaSNANot Applicable
Rhode IslandSNANot Applicable
South DakotaSNANot Applicable
TennesseeSNANot Applicable
UtahSNANot Applicable
VermontSNANot Applicable
VirginiaSNANot Applicable
WashingtonSNANot Applicable
West VirginiaSNANot Applicable
WisconsinSNANot Applicable
WyomingSNANot Applicable

Habitat

NatureServe records the Brown Trout in rivers, creeks, spring-fed brooks, riffles, pools, deep and shallow water, river mouths, bays and near-shore waters[10]. It is mostly found in cold streams with a medium or steep drop, though some populations live in lakes or go to sea[11]. It tends to use deeper, slower and warmer water than other trout[11]. It does best where the water holds plenty of dissolved oxygen, and shade over small streams helps[11]. It spawns in gravelly shallows and returns to the stream where it was born[11].

Habitat types recorded by NatureServe[10]

Size, diet and lifespan

Adults eat fish and small animals without backbones, such as insects[12]. Young fish in streams feed mostly on bugs drifting in the water, while large adults take fish, crayfish and other bottom-dwelling animals[13]. NatureServe records a typical length of 103 cm (41 in)[14]. The longest recorded lifespan in AnAge is 38 years[3]. A typical clutch size in AnAge is 8000 eggs[15]. Eggs hatch in 1 to 2 months, and fish usually mature in their 2nd or 3rd year[16].

Trait Value
Typical length[14] 103 cm (41 in)
Longest recorded lifespan (AnAge)[3] 38 years
Litter or clutch size[15] 8000
Food habits[12] Piscivore, Invertivore
Migration[17] non-migrant, local migrant

When to look for it

Feeding is most intense at twilight, the time around dusk and dawn[18]. The Brown Trout spawns in fall or early winter[16]. Some populations move between lakes or the sea and their spawning streams, while others stay put or move only locally[19][17]. Online records for the United States are most numerous in January, July and August, which reflects when people look and report, not how many fish there are[20].

January: 11,330 recordsJanFebruary: 768 recordsFebMarch: 2,354 recordsMarApril: 9,054 recordsAprMay: 9,167 recordsMayJune: 8,909 recordsJunJuly: 10,957 recordsJulAugust: 9,954 recordsAugSeptember: 8,406 recordsSepOctober: 9,336 recordsOctNovember: 1,673 recordsNovDecember: 3,104 recordsDec
US observation records on GBIF by month, all years. The three months with the most records are highlighted. Records show when people look and report, not how many animals there are[20].
Show records by month
MonthRecords
January11,330
February768
March2,354
April9,054
May9,167
June8,909
July10,957
August9,954
September8,406
October9,336
November1,673
December3,104

Where to see it

National Park Service species lists record Brown Trout as present in 56 park units[21]. Present means the park has a confirmed record, not that sightings are common.

And 32 more park units.

States with the most GBIF observation records: Pennsylvania, New Jersey, Wyoming, New York, New Mexico[9]. These counts follow where people look and report, not population size.

Questions people ask

Is the Brown Trout endangered?
No. It is not listed as endangered or threatened under the US Endangered Species Act[1]. NatureServe ranks it G5 (Secure) globally[2].
Is the Brown Trout native to the United States?
NatureServe records it as introduced, not native, in the states it lists, and USGS calls it a nonindigenous species in parts of the country[8][5].
What does the Brown Trout eat?
It eats insects, crayfish, snails and clams, and other fish[13]. NatureServe records adults as fish eaters and invertebrate eaters[12].
How big is a Brown Trout?
NatureServe records a typical length of 103 cm (41 in)[14].
How long does a Brown Trout live?
The longest recorded lifespan in AnAge is 38 years[3]. That is a record, not a typical lifespan.

Facts and sources

  1. Brown Trout is not listed as endangered or threatened under the US Endangered Species Act in USFWS ECOS data (checked 2026-10-30). USFWS ECOS
  2. NatureServe global conservation status rank for Brown Trout: G5 (Secure). NatureServe Explorer
  3. Maximum recorded lifespan in AnAge: 38 years. This is a record, not a typical lifespan. AnAge
  4. Brown Trout (Salmo trutta) is a fish in the family Salmonidae, order Salmoniformes. NatureServe Explorer
  5. NatureServe lists Brown Trout as introduced (not native) in: Alabama, Arkansas, Arizona, California, Colorado, Connecticut, the District of Columbia, Delaware, Georgia, Iowa, Idaho, Illinois, Indiana, Kentucky, Massachusetts, Maryland, Maine, Michigan,... NatureServe Explorer
  6. IUCN Red List category as recorded by NatureServe: Least concern. NatureServe Explorer
  7. NatureServe state ranks for Brown Trout (map and table on this page). NatureServe Explorer
  8. USGS lists Brown Trout as a nonindigenous aquatic species in parts of the United States (exotic). USGS NAS
  9. US states with the most GBIF observation records of Brown Trout: Pennsylvania, New Jersey, Wyoming, New York, New Mexico. Record counts follow observer effort, not population size. GBIF
  10. Habitat types NatureServe records for Brown Trout: Big river, Medium river, Creek, Spring/spring brook, High gradient, Moderate gradient, Low gradient, Riffle, Pool, Deep water, Shallow water, Bay/sound, River mouth/tidal river, Pelagic, Near shore. NatureServe Explorer
  11. NatureServe notes on habitat for Brown Trout. NatureServe Explorer
  12. Adult food habits recorded by NatureServe: Piscivore, Invertivore. NatureServe Explorer
  13. NatureServe notes on food for Brown Trout. NatureServe Explorer
  14. Typical length recorded by NatureServe: 103 cm (41 in). NatureServe Explorer
  15. Typical litter or clutch size in AnAge: 8000. AnAge
  16. NatureServe notes on reproduction for Brown Trout. NatureServe Explorer
  17. NatureServe migration category for Brown Trout: non-migrant, local migrant (populations can differ). NatureServe Explorer
  18. NatureServe notes on phenology for Brown Trout. NatureServe Explorer
  19. NatureServe notes on migration for Brown Trout. NatureServe Explorer
  20. GBIF observation records of Brown Trout in the US by month (chart on this page). GBIF
  21. NPSpecies park lists recording Brown Trout as present (list on this page). NPS NPSpecies

Status, range and habitat come from NatureServe Explorer (CC BY 4.0) and USFWS ECOS at the snapshot date. Listings change by federal rule. State lists are where NatureServe records the species, not a promise that you will see it there. Never name a place smaller than a state. GBIF and park records count observations and checklists. They show where and when people report the species, not how many animals live there.

NatureServe. 2026. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org. (Accessed: October 30, 2026). Licensed under CC BY 4.0; SpeciesFacts selected and summarized it.

Photo: Duane Raver, U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons.