‘Trout’ is the general name for a number of different types of freshwater fish of Salmonidae family.
There are a wide variety of trout species living in the UK, each with their own distinctive look, diet and characteristics. Here is a guide to some of the most common types of trout found in the UK.
Brown trout, or the salmo trutta, are a freshwater fish native to Europe and Asia. The species is one of only few native to the UK and are known for their brown and golden colouring. Their belly is usually white or yellow, with silver or yellow sides and red coloured spots.
The freshwater diet of Brown trout usually consist in flying insects, other fish, mice, invertebrates from the streambed, frogs and birds. However, they have an extremely high reliance on insect larvae and adults which is why they are a popular target for fly fishing.
Brown trout are active both in the daytime and at night, and will often stay in the same position in the river for long periods of time – except for during spawning.
The Rainbow trout, or Oncorhynchus mykiss, was brought into the UK from North America. They have fast growing rates and do not need such high water quality as the native Brown trout. Though they have a similar shape to the Brown trout, they are distinguishable by their pinkish sheen, generally lighter colour, and more heavily spotted anal and tail fins.
The diet of the Rainbow trout is varied, and they will eat most of what they can find. Younger fish include a large proportion of insects in their diet, and they will rely more on eating fish as they grow older.
Rainbow trout are especially known for their ability to jump three to four times their body’s length, as well as being able to detect the slightest movements in the water from insects at large distances.
The Tiger trout is a hybrid of the Brown trout and the Brook trout, however it looks completely unique with its marking along the side, looking like a tiger’s stripes. This species is very rare, due to the fact that each of the species of the hybrid are of a separate genus and have different numbers of chromosomes – therefore the Tiger trout cannot reproduce.
The Tiger trout can often be aggressive, eating smaller fish and fighting with other species such as Rainbow trout. They also feed off insects.
Ferox are extremely large trout, where the word itself means ‘ferocious’. They are characterised by a head that grows out of proportion to its body, which is what allows them to eat larger prey. Each individual Ferox can differ in its spots, colouring and size.
The young Ferox trout feeds on invertebrates and small insects. However, as they age they tend to feed on other fish, including smaller Brown trout.
Ferox trout are actually larger Brown trout, and only a small proportion of Brown trout will become Ferox, which is why they are so rare. However, they can be found all across the UK, and once they start eating fish they can grow rapidly – up to over a metre in length.
The Grayling is typically found in more mountainous areas of Europe, and is not found in Ireland or Northern Scotland. They have a very high dorsal fin which helps to distinguish them from other salmonid fish, and their colour is generally purple-blue.
The Grayling tends to feed at dawn and dusk, eating caddis larvae in large quantities (though larger Grayling may also feed on small fish).
Grayling are best suited to fast-flowing streams with high water quality and cool water. They often feed on drifting prey despite their underslung mouths.