The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Salmo trutta × Salvelinus fontinalis
Salmo trutta × Salvelinus fontinalis
(tiger trout)
Exotic Hybrid

Copyright Info
Salmo trutta × Salvelinus fontinalis

Common name: tiger trout

Injurious: This species is listed by the U.S. Fish and Wildlife Service as injurious wildlife.

Identification: Buss and Wright (1958); Brown (1966); Suzuki (1974); Becker (1983); International Game Fish Association (1994).

Size: Probably 70-103 cm.

Native Range: Mainly an artificial hybrid, but has been known to occur in nature (Brown 1966; Allan 1977; International Game Fish Association 1994). (Even where it occurs "naturally," it is the result of stocking a nonindigenous species, the brown trout).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Salmo trutta × Salvelinus fontinalis are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AR200520051Little Red
CA196620202California Region; Truckee
CO199320204Colorado Headwaters; South Platte; Upper Arkansas; Upper Arkansas-Lake Meredith
ID201720204Middle Salmon-Panther; Pahsimeroi; Palisades; Teton
IL197719771Lake Michigan
MT195019903Lower Yellowstone-Sunday; Shields; Upper Clark Fork
NV199220224Long-Ruby Valleys; Meadow Valley Wash; Thousand-Virgin; Upper Humboldt
NH198019902Headwaters Connecticut River; Piscataqua-Salmon Falls
NY198819891Southern Long Island
OR201620161North Umpqua
SD198919891Lower Belle Fourche
UT199620226Blacks Fork; Duchesne; Price; Provo; San Rafael; Upper Bear
WV1986199510Cheat; Elk; Gauley; Greenbrier; Little Kanawha; Lower New; Middle New; Twelvepole; Tygart Valley; Upper Kanawha
WI197319838Castle Rock; Lake Michigan; Lower Chippewa; Manitowoc-Sheboygan; Menominee; Namekagon; Upper Fox; Wolf
WY197019703Lower Laramie; New Fork; Upper Wind

Table last updated 7/14/2024

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: Some stocked intentionally as sport fish; others occur "naturally" as a result of brown trout stockings in native brook trout range (Holton 1990).

Status: Maintained by stocking. In Montana, some hybridization occurs "naturally" because both species are stocked in the same rivers (Holton 1990).

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: This hybrid is the result of a cross between a female brown trout and a male brook trout. It is primarily a hatchery produced fish.  Mortality of eggs and alevin is high because of lack of relatedness between parent species. Survivors are not reproductively viable (International Game Fish Association 1994). This hybrid is more resistant to fungus mortality related to spawning stress than are the parental species (Becker 1983).

References: (click for full references)

Insider Viewpoint. 2001. Fishing Records – Nevada. Insider Viewpoint Magazine. 3 pp.

Rasmussen, J.L. 1998. Aquatic nuisance species of the Mississippi River basin. 60th Midwest Fish and Wildlife Conference, Aquatic Nuisance Species Symposium, Dec. 7, 1998, Cincinnati, OH.

Other Resources:
Fact Sheet for Salmo trutta - USGS Nonindigenous Aquatic Species Database

Fact Sheet for Salvelinus fontinalis - USGS Nonindigenous Aquatic Species Database

Author: Fuller, P.

Revision Date: 3/5/2012

Peer Review Date: 3/5/2012

Citation Information:
Fuller, P., 2024, Salmo trutta × Salvelinus fontinalis: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=933, Revision Date: 3/5/2012, Peer Review Date: 3/5/2012, Access Date: 7/14/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/14/2024].

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