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What the sources say

Rainbow TroutOncorhynchus mykiss

Every figure, record and mechanism on the Rainbow Trout profile was written from a source, and this is the working table behind it: 44 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Hammerson & Bogutskaya 2024

Hammerson & Bogutskaya (2024). Oncorhynchus mykiss. The IUCN Red List of Threatened Species 2024: e.T166481A18229476.

The page saysLeast Concern
The source saysIUCN Red List category: Least Concern (LC).Note: Assessed 2020 (IUCN taxon 166481); category read through GBIF's copy of the Red List.
The page saysThe Red List rates the species Least Concern.
The source saysIUCN Red List category: Least Concern (LC).

Source
02

Yano et al. 2012

Yano et al. (2012). An Immune-Related Gene Evolved into the Master Sex-Determining Gene in Rainbow Trout, Oncorhynchus mykiss. Current Biology.

The page saysA stream fish whose sex is set by a Y-chromosome gene unrelated to any known sex-differentiating gene.
The source sayssdY is a novel vertebrate master sex-determining gene not related to any known sex-differentiating gene
The page saysOne gene, sdY, decides whether it becomes male or female
The source saysThe targeted inactivation of sdY in males using zinc-finger nuclease induces ovarian differentiation, and the overexpression of sdY in females using additive transgenesis induces testicular differentiation.
The page saysit is expressed only in the testis
The source saysan unknown gene expressed only in the testis
The page saysThe sdY gene is a vertebrate master sex-determining gene not related to any known sex-differentiating gene.
The source sayssdY is a novel vertebrate master sex-determining gene not related to any known sex-differentiating gene
The page sayssexually dimorphic on the Y chromosome
The source saysThis gene, named sdY for sexually dimorphic on the Y chromosome
The page saysResearchers who switched it off in males, using a tool called zinc-finger nuclease, got fish that grew ovaries.
The source saysThe targeted inactivation of sdY in males using zinc-finger nuclease induces ovarian differentiation
The page saysResearchers who added sdY to females got fish that grew testes.
The source saysthe overexpression of sdY in females using additive transgenesis induces testicular differentiation

Source
03

Thomas, Allain & Owen 2021

Thomas, Allain & Owen (2021). Predation and ingestion of a barred grass snake Natrix helvetica by a rainbow trout Oncorhynchus mykiss in Lot, France. Herpetological Bulletin.

The page saysIn 2020 a trout of about 30 centimeters was caught in a small French stream.
The source saysAt around 16:00 h on the 18th July 2020, a rainbow trout, recently released for the purpose of recreational fishing, was caught by HO while angling along the Saint-Matré (a small stream) in Grézels, Lot, FranceNote: The 30 cm figure is quoted in the claim 'a trout of about 30 centimeters' (The fish was a mature specimen, roughly 30 cm long).
The page saysa trout of about 30 centimeters
The source saysThe fish was a mature specimen, roughly 30 cm long.
The page saysInside it was a live hatchling grass snake about 20 centimeters long.
The source saysa live hatchling barred grass snake was found inside the gastrointestinal tract (Fig 1). The hatchling snake measured approximately 20 cm long
The page sayswhat evidence there is suggests fish rarely eat barred grass snakes, and only small ones
The source saysWhat evidence there is suggests that the consumption of N. helvetica by fish is rare and restricted to small specimens.Note: 'Only small ones' is the source's 'restricted to small specimens'.
The page saysAn angler in France gutted a trout of about 30 centimeters and found a live hatchling grass snake inside it.
The source saysThe trout was gutted minutes after capture and surprisingly, a live hatchling barred grass snake was found inside the gastrointestinal tractNote: The 30 cm figure is quoted in the claim 'a trout of about 30 centimeters' (The fish was a mature specimen, roughly 30 cm long).
The page saysThe authors say the evidence suggests fish eating these snakes is rare.
The source saysWhat evidence there is suggests that the consumption of N. helvetica by fish is rare and restricted to small specimens.

Source
04

FishBase

Oncorhynchus mykiss (Walbaum, 1792), Rainbow trout. FishBase.

The page saysClear, cold headwaters, creeks, rivers and lakes of the Pacific Slope of North America, now introduced widely
The source saysInhabit clear, cold headwaters, creeks, small to large rivers, lakes, and intertidal areas
The page saysAquatic and terrestrial invertebrates and small fishes
The source saysFeed on a variety of aquatic and terrestrial invertebrates and small fishes.
The page saysTheir native range runs down the Pacific Slope, from the Kuskokwim River drainage in Alaska to the Otay River drainage in California.
The source saysPacific Slope from Kuskokwim River drainage in Alaska to Otay River drainage in California, USA.
The page saysFishBase gives a common length of about 60 centimeters.
The source sayscommon length : 60.0 cm TL
The page saysThey feed on aquatic and terrestrial invertebrates and small fishes.
The source saysFeed on a variety of aquatic and terrestrial invertebrates and small fishes.
The page saysAt spawning time the female digs a pit in the gravel while a male courts her or drives other males away.
The source saysThe female finds a spot and digs a pit. While digging, an attendant male courts her or is busy driving away other males.Note: 'In the gravel' is ADW's: 'Adult rainbow trout and steelhead lay their eggs in a series of nests in gravel.' ADW's 'digs the nest with her anal fin' was cut: salmonid females dig with the tail, and FishBase names no fin.
The page saysA female makes 700 to 4,000 eggs per spawning event.
The source saysFemales produce from 700 to 4,000 eggs per spawning event
The page saysRainbow trout are often hatched and stocked into rivers and lakes, especially to attract recreational anglers.
The source saysCultured in many countries and is often hatched and stocked into rivers and lakes especially to attract recreational fishers
The page saysnow introduced widely
The source saysWidely introduced and established in Canada and USA
The page saysFishBase gives 60 centimeters as a common length.
The source sayscommon length : 60.0 cm TL
The page saysIts record is 123 centimeters, and the heaviest published weight is 25.9 kilograms.
The source saysMax length : 123 cm TL male/unsexed; (Ref. 120611 ); common length : 60.0 cm TL male/unsexed; (Ref. 5504 ); max. published weight: 25.9 kgNote: 'Record' is FishBase's max length; 'heaviest published weight' is its max. published weight.
The page saysFishBase lists them as widely introduced and established in Canada and the USA, and elsewhere in the world.
The source saysWidely introduced and established in Canada and USA, including Arctic, Atlantic, Great Lakes, Mississippi River, and Rio Grande basins, and elsewhere in the world
The page saysIt says several countries report adverse ecological impact after introduction.
The source saysSeveral countries report adverse ecological impact after introduction.
The page saysFishBase lists a maximum length of 123 centimeters, a maximum published weight of 25.9 kilograms and a maximum reported age of 11 years.
The source saysMax length : 123 cm TL male/unsexed; (Ref. 120611 ); common length : 60.0 cm TL male/unsexed; (Ref. 5504 ); max. published weight: 25.9 kg (Ref. 120611 ); max. reported age: 11 years
The page saysRainbow trout live in clear, cold headwaters, creeks, rivers, lakes and intertidal areas.
The source saysInhabit clear, cold headwaters, creeks, small to large rivers, lakes, and intertidal areas
The page sayswith another native population on Russia's Kamchatka Peninsula
The source saysEastern Pacific: Kamchatkan PeninsulaNote: FishBase continues: records outside Kamchatka 'probably represent migrating or straying Kamchatkan steelhead ... rather than the established native population'.

Source
05

NOAA Fisheries

Steelhead Trout. NOAA Fisheries.

The page saysNOAA calls steelhead a unique life-history type of rainbow trout
The source saysSteelhead are a unique life-history type of rainbow trout.
The page saysthe ones that go to sea typically grow larger than the ones that stay
The source saysSteelhead (anadromous rainbow trout) that migrate to the ocean typically grow larger than the individuals that remain in freshwater.
The page saysSteelhead can reach about 30 pounds (roughly 14 kilograms)
The source saysUp to approximately 30 poundsNote: Metric figure is a conversion.
The page saysNOAA says they live up to 11 years, usually 5 to 8.
The source saysUp to 11 years, though usually 5 - 8 yearsNote: Quick Facts figure is for steelhead, the sea-run form.
The page saysalong the West Coast, 11 steelhead populations are protected under the Endangered Species Act
The source saysAlong the West Coast, 11 species of steelhead are protected under the Endangered Species ActNote: NOAA's '11 species' are the Distinct Population Segments it lists, which the ESA treats as species; page last updated 09/24/2026.
The page saysSome rainbow trout stay in fresh water all their lives.
The source saysThose that stay in fresh water all their lives are called rainbow trout (nonanadromous).
The page saysOthers migrate to the ocean and come back to spawn, and those are called steelhead.
The source saysSteelhead (anadromous rainbow trout) that migrate to the ocean typically grow larger than the individuals that remain in freshwater. They then return to freshwater to spawn.
The page saysA steelhead is a rainbow trout that heads out to sea.
The source saysSteelhead (anadromous rainbow trout) that migrate to the ocean
The page saysUnlike most other Pacific salmonids, the group that includes salmon and steelhead, they do not necessarily die after spawning.
The source saysUnlike most other Pacific salmonids (i.e., salmon and steelhead ), steelhead are iteroparous, meaning they do not necessarily die after spawning
The page saysTrout that stay in fresh water all their lives keep the name rainbow trout, and the sea-going ones typically grow bigger.
The source saysSteelhead (anadromous rainbow trout) that migrate to the ocean typically grow larger than the individuals that remain in freshwater.Note: 'All their lives' is NOAA's: 'Those that stay in fresh water all their lives are called rainbow trout (nonanadromous).' (claim 'Some rainbow trout stay in fresh water all their lives.')
The page saysand 40 inches (about a meter)
The source saysUp to approximately 40 inchesNote: Metric figure is a conversion; steelhead Quick Facts.
The page saysSome rainbow trout stay in fresh water all their lives, while steelhead migrate to the ocean and then return to spawn
The source saysThose that stay in fresh water all their lives are called rainbow trout (nonanadromous). Steelhead (anadromous rainbow trout) that migrate to the ocean typically grow larger than the individuals that remain in freshwater. They then return to freshwater to spawn.

Source
06

Animal Diversity Web, University of Michigan Museum of Zoology

Oncorhynchus mykiss, Coast rainbow trout. Animal Diversity Web, University of Michigan Museum of Zoology.

The page sayswhere they are introduced they can outcompete native trout species
The source sayswhere they are introduced, they can outcompete native trout species

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.