The Brown Trout (Salmo trutta) is a cold-water freshwater fish known for its distinctive spotted appearance, adaptability and popularity among anglers. Although native to Europe and parts of western Asia, Brown Trout have been introduced throughout many parts of the world and are now well established across North America.
In Ontario, the species was introduced from Europe in 1913 and can now be found throughout the Great Lakes and their tributaries, as well as many streams and stocked waters in southern Ontario.
Brown Trout belong to the salmon family, Salmonidae, making them relatives of Rainbow Trout, Brook Trout, Atlantic Salmon and other salmonids.
Identification
Brown Trout are easily recognized by their brown to golden-brown appearance and distinctive spotting.
Their backs are generally brown, while their sides can range from pale brown to silvery. The belly is typically white. Dark spots are common along the body and are often surrounded by lighter rings. Some fish also display noticeable red or orange spots.
Common identifying characteristics include:
- Brown or olive-brown back
- Pale brown, golden or silvery sides
- White belly
- Dark spots, often surrounded by lighter rings
- Red or orange spots on many individuals
- Relatively few spots on the tail
- Short, stocky area between the body and tail
- Adipose fin between the dorsal fin and tail
Ontario notes that this is the only salmon or trout in the province with orange coloration on the adipose fin, making it a useful identification feature.
Colour and markings can vary considerably depending on habitat, age and whether the fish lives in an inland waterbody or the Great Lakes.
Where Are They Found?
Brown Trout are not native to Ontario. They were introduced from Europe and have since become established in many waters throughout the province.
Today, populations can be found throughout the Great Lakes and their tributaries, as well as streams and stocked creeks in southern Ontario.
They are particularly abundant in areas associated with Lake Ontario, Georgian Bay, Great Lakes tributaries and inland stocked waters.
Outside Ontario, introduced populations have become established across large portions of Canada and the United States.
Preferred Habitat
These trout require relatively cold, clean and well-oxygenated water.
They can inhabit both lakes and flowing waters and are commonly associated with:
- Cool rivers and creeks
- Streams with moderate current
- Gravel bottoms
- Riffles and pools
- Stream-fed ponds
- Lake shallows
- Areas offering cover and suitable feeding opportunities
Ontario’s freshwater fish database identifies approximately 15–18°C (59–64°F) as a preferred water temperature range.
Their ability to occupy both lakes and rivers has helped Brown Trout establish populations across a wide variety of suitable cold-water habitats.
Diet and Feeding
Brown Trout are carnivorous and their diet changes as they grow.
Young fish rely heavily on small aquatic organisms and insects. Larger individuals increasingly consume larger prey and may become effective fish predators.
Their diet can include:
- Aquatic insects
- Insect larvae
- Crustaceans
- Worms
- Small fish
- Fish eggs
- Other available aquatic prey
Food availability varies between streams, rivers and large lakes, so the exact diet of a population depends heavily on its environment.
Larger individuals can become aggressive predators and may consume surprisingly large prey compared with their own body size.
Size and Weight
Size varies considerably depending on habitat.
Ontario lists a general length of approximately 20 to 60 centimetres (8 to 24 inches) and weights ranging from approximately 0.5 to 4.5 kilograms (1 to 9.5 pounds). Great Lakes fish can grow larger than many inland populations.
Exceptional individuals can become considerably larger.
The Ontario record is 15.6 kilograms (34.4 pounds), demonstrating the impressive size these trout can attain under favourable conditions.
Growth depends on factors including food availability, water temperature, habitat quality and the type of waterbody the fish inhabits.
Lifespan
Brown Trout are relatively long-lived compared with many smaller freshwater species.
Ontario’s freshwater fish database lists a lifespan of approximately 5 to 12 years, although longevity can vary between populations.
Fish living in productive environments with abundant food and favourable conditions may survive long enough to reach impressive sizes.
Spawning and Reproduction
Spawning takes place during the fall, generally during October and November in Ontario.
Females seek areas with clean gravel and suitable flowing water. Using their tails, they create depressions in the gravel known as redds, where eggs are deposited and fertilized.
After spawning, the eggs remain within the gravel during development.
Unlike some freshwater fish that actively guard their offspring, adult trout do not remain to protect the eggs or newly hatched young.
Clean spawning gravel and good water quality are therefore important to successful natural reproduction.
Behavior and Seasonal Movement
Brown Trout are adaptable predators whose behaviour changes with season, water temperature and habitat.
In streams, they frequently use pools, current breaks, undercut banks, rocks and other structures that provide both cover and access to passing food.
Fish living in larger lakes may travel much greater distances in response to water temperature and food availability.
As fall approaches, mature fish become increasingly focused on spawning and may move into tributaries or suitable spawning areas.
Water temperature plays an especially important role in their activity and distribution because they are a cold-water species.
Brown Trout vs. Brook Trout
Despite their names, Brown Trout and Brook Trout aren’t especially close relatives within the salmon family.
Brown Trout belong to the genus Salmo, while Brook Trout belong to Salvelinus, making Brook Trout technically a type of char.
Appearance can also help distinguish them.
Brown Trout generally have dark and reddish spots against a lighter brown or golden background. Brook Trout typically display light-coloured markings against a darker background and often have distinctive worm-like markings along the back.
Correct identification is particularly important for anglers because fishing regulations can differ between trout species and individual waterbodies.
Fishing for Brown Trout
Brown Trout are highly valued as sport fish because of their size, strength and sometimes challenging behaviour.
They can be caught using several techniques, including fly fishing, casting, drifting and trolling.
Common presentations include:
- Flies
- Spinners
- Spoons
- Small plugs
- Jigs
- Worms
- Roe
Ontario notes that Great Lakes fish can be targeted by trolling, while tributary fish are commonly pursued with small spinners, plugs or bait presented beneath floats.
Fishing regulations vary by province, fishing zone and individual waterbody, so anglers should always check current regulations before fishing.
Interesting Brown Trout Facts
Brown Trout are members of the Salmonidae family, which includes trout, salmon, char and whitefish.
They are an introduced species in Ontario rather than a native fish. Their introduction to Ontario waters dates back to 1913.
The scientific name is Salmo trutta.
Individual appearance can vary dramatically. Some fish develop rich golden-brown coloration and pronounced red spots, while Great Lakes individuals can appear much more silvery.
Great Lakes fish can also grow considerably larger than many inland populations.
Their ability to survive in streams, rivers and large lakes has helped them establish populations throughout many parts of North America.
Frequently Asked Questions
Are Brown Trout native to Ontario?
No. They were introduced to Ontario from Europe in 1913 and have since become established in the Great Lakes, tributaries and numerous inland waters.
What do Brown Trout eat?
Their diet includes aquatic insects, larvae, crustaceans, small fish and other available aquatic prey. Larger individuals generally become increasingly predatory.
How big do they get?
Ontario lists a typical length of approximately 20 to 60 centimetres, or 8 to 24 inches. Larger fish are possible, particularly in highly productive waters such as the Great Lakes.
Where do they live?
They inhabit cold-water lakes, rivers, creeks and streams. In Ontario, they occur throughout the Great Lakes and tributaries and in numerous southern Ontario streams and stocked waters.
When do they spawn?
Spawning generally occurs during fall. Ontario’s freshwater fish database identifies October and November as the primary spawning months.
Are Brown Trout and Brook Trout the same fish?
No. They are separate species. Brown Trout are Salmo trutta, while Brook Trout are Salvelinus fontinalis and are technically members of the char group.
How long do they live?
Ontario’s freshwater fish database lists a lifespan of approximately 5 to 12 years.