Brown Trout Fish - Facts, Information & Pictures (original) (raw)
The Brown Trout (Salmo trutta) is normally considered to be native to Europe and Asia. There are also landlocked populations far from the oceans, for example in Greece and Estonia. The Brown Trout can be found all over the British Isles in lakes or rivers where the water is clean and well aerated. The Brown Trout feeds on insects and larvae, shellfish, worms and small fish.
According to the locality, adult Brown Trout may weigh from a few ounces to several pounds.
Conservation
The Brown Trout is not considered to be endangered although some are under various degrees of stress, mainly through habitat degradation, over-harvest and artificial propagation leading to introgression, which is the introduction of genes from one species into the gene pool of another, occurring when mating between the two produces fertile hybrids.
Habitat
The Brown Trout prefers cold, well-oxygenated upland waters, especially large streams in mountainous areas. Cover is important to trout and they are more likely to be found where there are submerged rocks, undercut banks and overhanging vegetation.
Appearance
The Brown Trout is a medium sized fish, growing to 20 kilograms or more in some localities, although in many smaller rivers a mature weight of 1 kilogram or less is common. Despite its name, it can be of almost every colour, from silver in its sea-going form to almost black, with a dark back and slightly paler belly. Their sides are covered with spots and rings of many colours and the tail is not forked.
Behaviour and Diet
Brown Trout may live for several years, although as with the Atlantic Salmon there is a high proportion of male death after spawning, and probably fewer than 20% of female kelts recover from spawning. The migratory forms grow to significantly larger sizes and may live longer. Brown Trout are active both by day and by night and are opportunistic feeders. While in fresh water, their diet will frequently include invertebrates from the streambed, small fish, frogs and insects flying near the water’s surface.
Spawning
The spawning behaviour of the Brown Trout is similar to that of the closely related Atlantic Salmon. A typical female Brown Trout produces about 2,000 eggs per kilogram of body weight at spawning. Brown Trout rarely form hybrids, almost invariably infertile, with other species. One such example is the Tiger Trout, a hybrid with the Brook Trout.
The Sea Trout
One of the most interesting aspects of the Brown Trout as a species is that it exists in both resident and migratory forms, and the differences between the two can be striking enough that they were once considered entirely separate species. The migratory form, commonly known as the Sea Trout, spends part of its life at sea before returning to freshwater rivers to spawn. During its time in the ocean it grows considerably faster than its river-bound relatives, feeding on a richer and more varied diet of marine fish and crustaceans. The silver colouring of the Sea Trout is a direct result of this saltwater phase, and fish returning from the sea are often barely recognisable as the same species as the spotted, dark-backed Brown Trout of an upland stream.
Both forms belong to the same species and are capable of interbreeding where their ranges overlap, which adds further complexity to the already considerable variation seen within Brown Trout populations across their range.
Brown Trout and Fly Fishing
The Brown Trout holds a special place in the history and culture of fly fishing. For centuries it has been the primary quarry of anglers across Britain, Ireland and mainland Europe, and the pursuit of wild Brown Trout in clear, fast-flowing rivers is considered by many to be the most demanding and rewarding form of the sport. The fish is prized not only for its fighting qualities when hooked but also for the skill required to present a fly convincingly enough to deceive it.
Brown Trout are notoriously selective feeders, particularly in waters where they have experienced significant fishing pressure, and they can become extremely wary of unnatural movement or presentation on the surface. This intelligence and caution has elevated the Brown Trout to something of an iconic status among freshwater fish, and the rivers and lochs where wild populations thrive are highly valued both by anglers and by conservationists.
Brown Trout Beyond Europe
Although native to Europe and parts of Asia, the Brown Trout has been introduced to many other parts of the world, including North America, New Zealand, Australia, South Africa and South America. In some of these regions it has established thriving wild populations and become an important species for recreational fishing. In others, however, its introduction has had negative consequences for native fish species with which it competes for food and habitat, making it a controversial addition to the ecosystems it now inhabits beyond its original range.
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What is a Brown Trout?
The Brown Trout (Salmo trutta) is normally considered to be native to Europe and Asia. There are also landlocked populations far from the oceans, for example in Greece and Estonia.
What do Brown Trouts eat?
While in fresh water, their diet will frequently include invertebrates from the streambed, small fish, frogs and insects flying near the waters surface.
Where do Brown Trouts live?
The Brown Trout (Salmo trutta) is normally considered to be native to Europe and Asia.
How long do Brown Trouts live?
Brown Trout may live for several years although, as with the Atlantic salmon, there is a high proportion of death of males after spawning and probably fewer than 20% of female kelts recover from spawning.
How big do Brown Trouts get?
According to the locality, adult Brown Trout may weigh from a few ounces to several pounds.
Sources & References
Cite This Page
APA
Joanne Spencer (2026, April 9). Brown Trout. Animal Corner. Retrieved 2026, May 18, from https://animalcorner.org/animals/brown-trout/
MLA
Joanne Spencer. "Brown Trout." Animal Corner, 2026, April 9, https://animalcorner.org/animals/brown-trout/.
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Joanne Spencer is the founder and lead writer at Animal Corner, where she has been researching and writing about wildlife since 2005. With over 19 years of experience in animal behavior, ecology, and conservation, Joanne has authored hundreds of species profiles and educational guides covering mammals, birds, reptiles, amphibians, and marine life. Her work draws on field observations, peer-reviewed research, and partnerships with conservation organizations to deliver accurate, accessible animal information for students, educators, and wildlife enthusiasts worldwide.