Rainbow trout

These gloriously coloured fish are extremely common across Britain due to their ability to adapt to Stillwater. This makes them the obvious choice species of trout to grow on within man-made lakes are reservoirs across the country.

The average size of a rainbow trout in the British Isles will be around the 1-4lb mark, but they can grown up to 30lb.



There’s no mistaking the rainbow trout. It has the classic ‘trout shape’ in that it’s sleek, has a pronounced dorsal fin and substantial concave tail fin.

The head of the rainbow trout is a lot more rounded than that of the brown trout, particularly around the snout.

The colours across the trout’s back and flanks make identification quite easy. The back has an olive sheen that blends into its silvery flanks. Running from the head right to the tail is a fantastic red band – almost holographic. Then there are a multitude of tiny spots - hundreds of them – dotted across the back, flanks, fins and tail. There are no spots on the underside of the rainbow trout.

Some rainbow trout living in deep and crystal clear reservoirs may not have the red band running along the flank. Instead they will be pure silver, overlaid with hundreds of dots.



Insects are a trout’s favourite food, no matter at what stage the insect life cycle may be, it is not safe when there are trout around!

They are aggressive feeders too - they prey on small fish as well as insect life and crustaceans.

To catch a trout is relatively easy as they will attack almost anything if they are hungry. Small spinners, spoons and plugs take some beating, as do worms and maggots, but the ‘accepted method’ is to fly fish for them.

The choice of fly, and associated lines, is not straightforward as you need to assess the depth at which the trout may be feeding and present your fly to suit.


The natural breeding of the rainbow trout within the British Isles is quite rare – it only occurs in very few river systems as the conditions have to be perfect for the eggs to develop and hatch.

The fish prepare to breed between January and April. The males darken (often known at this time as black fish) and develop a pronounced hook on the lower jaw together with a vivid orange mark on the gills, extending down the flanks.

The vast majority of rainbow trout in the country are farm reared and stocked into mostly. Some keepers of rivers introduce rainbow trout too.