Rainbow Trout

Rainbow Trout facts at a glance

How big is a rainbow trout?

An adult rainbow trout measures 60 cm long — about 35% of the height of an average adult person (1.73 m) — and weighs around 3.0 kg, about 4% of an average adult’s body weight (70 kg).

What is a group of rainbow trouts called?

Explore more animal collective nouns and baby animal names .

Fly fishing icon

Rainbow trout rise to dry flies on the surface, making them the quintessential fly-fishing species. Clear mountain streams of the American West — Montana, Idaho, Colorado — built a global angling culture around wild rainbow and cutthroat trout.

Steelhead life history

Some coastal populations ('steelhead') migrate to the ocean and return to natal rivers to spawn, growing larger and more silvery than resident river fish. Dams, water extraction, and warming streams threaten these anadromous runs across the Pacific Northwest.

Global stocking

Rainbow trout have been introduced to every continent except Antarctica for food and sport. They can hybridise with native trout and outcompete local species, making introductions controversial in places like New Zealand, Chile, and the Appalachian Mountains.

Aquaculture and wild genetics

Farm-raised rainbow trout supply supermarkets worldwide. Hatchery supplementation of wild streams raises questions about genetic dilution of native strains. Wild populations in the Pacific Northwest remain the evolutionary heartland of the species.

Did you know? Rainbow Trout facts

• Rainbow trout are salmonid fish native to Pacific North America, named for the pink lateral stripe along silver sides.
• Rainbow trout are in the same genus as Pacific salmon. Steelhead are sea-run rainbow trout. Salmon typically die after spawning; many trout survive to spawn again.
• A rainbow trout that migrates to the ocean and returns to freshwater to spawn — larger and more silvery than river-resident rainbows.
• Aquatic insects, terrestrial insects that fall on the water, crustaceans, and small fish — diet shifts with size and habitat.
• Pacific drainages from Alaska through California and inland to Idaho and Nevada — not the eastern United States, where they are introduced.
• Conservation: Least Concern (IUCN).

Diet & feeding

Rainbow Trout feeds primarily as a carnivore — insects, crustaceans, and small fish. Some coastal populations ('steelhead') migrate to the ocean and return to natal rivers to spawn, growing larger and more silvery than resident river fish. Dams, water extraction, and warming streams threaten these anadromous runs acros

Adaptations

• Rainbow trout rise to dry flies on the surface, making them the quintessential fly-fishing species. Clear mountain streams of the American West — Montana, Idaho, Colorado — built a global angling culture around wild rainbow and cutthroat trout.
• Some coastal populations ('steelhead') migrate to the ocean and return to natal rivers to spawn, growing larger and more silvery than resident river fish. Dams, water extraction, and warming streams threaten these anadromous runs across the Pacific Northwest.

Behaviour & ecology

• Rainbow trout rise to dry flies on the surface, making them the quintessential fly-fishing species. Clear mountain streams of the American West — Montana, Idaho, Colorado — built a global angling culture around wild rainbow and cutthroat trout.
• Some coastal populations ('steelhead') migrate to the ocean and return to natal rivers to spawn, growing larger and more silvery than resident river fish. Dams, water extraction, and warming streams threaten these anadromous runs across the Pacific Northwest.
• Rainbow trout have been introduced to every continent except Antarctica for food and sport. They can hybridise with native trout and outcompete local species, making introductions controversial in places like New Zealand, Chile, and the Appalachian Mountains.

Communication

• Lateral-line and visual cues coordinate schooling, courtship, or territorial behaviour.
• Some species produce low-frequency sounds or drumming for spawning or defence.

Habitat & range

Cold rivers, lakes, and streams; anadromous steelhead in coastal rivers

Ecological role

Rainbow Trout acts as a predator that helps regulate prey populations and maintain balance in cold rivers, lakes, and streams; anadromous steelhead in coastal rivers.

Conservation status of the Rainbow Trout

Sources & references

This guide is compiled and reviewed against established zoological and conservation references. Key sources for the Rainbow Trout:

• IUCN Red List of Threatened Species

  Conservation status (Least Concern) reflects the IUCN Red List category for Oncorhynchus mykiss.

• iNaturalist — observations & photos

  Search citizen-science observations and community IDs for Oncorhynchus mykiss. Useful for range checks and recent sightings — not a substitute for formal Red List status.

• GBIF — occurrence data

  Global Biodiversity Information Facility species search for Oncorhynchus mykiss. Explore published occurrence records used in range research.

• IUCN Red List — Oncorhynchus mykiss.

  Conservation status (Least Concern) and population trends.

• Animal Diversity Web — Oncorhynchus mykiss. University of Michigan Museum of Zoology.

  Life history, morphology, and range.

• Global Animal Guide editorial standards

  How we research, source, review, and update every guide for accuracy.