The Fascinating Tale of the Rainbow Trout

An Introduction to Rainbow Trout

The rainbow trout (Oncorhynchus mykiss) is a truly beautiful species of fish. From their bold, striking coloration to their majestic feeding habits and the sheer size they are able to grow to, it’s really no wonder that many people are interested in this famous freshwater creature. There really is a lot to know about this species, and throughout this article we will try to cover the basics.


Where the rainbow came from

As fish are able to swim all over the place, it is often difficult to trace where a species may have originated from. However, much research into the history of the rainbow trout has determined that this particular species is native to freshwater rivers and streams that run into the Pacific Ocean in both Asia and North America. When these fish enter the ocean and live in saltier water (known as becoming “sea-run”), they are known as steelhead. Amazingly, almost all sea-run trout still return to their freshwater homelands to spawn, even after living in the ocean for two or three years.

Although these fish were once native to the Pacific Ocean and its surrounding freshwater tributaries, they have been introduced to waterways worldwide, on every continent except for Antarctica. This is primarily for sport, as a great number of people enjoy fishing for rainbow trout, and anglers often travel great distances to find trophy trout; the wild, huge fish that live in their own private section of a pristine, untouched river somewhere in the wilderness of a number of countries around the world.

The life of a rainbow

Video from Freshwater Fisheries Society of BC

The life of these fish can vary greatly depending on whether they live only in freshwater or spend large amounts of time in salt water. This species commonly spawns throughout the spring time, predominantly from March to June in the northern hemisphere, and September to November in the southern hemisphere. The water is sufficiently warm at this time to facilitate spawning, and some trout travel great distances to arrive at a suitable spawning area.

Remarkably, these fish return to their original hatching ground for spawning. There is much speculation regarding how they are able to display such an incredible sense of direction, and the migration has been referred to as one of the most remarkable journeys made by a species. Popular spawning waters are usually well oxygenated, shallow river beds with gravel bottoms. Fish residing in lakes tend to find well vegetated areas as these ensure a constant supply of food and nutrients, and will also seek out any creeks or streams that enter the lake.

If you’ve ever had the opportunity to watch spawning fish, you’ll know that the process is intricate and rather fascinating. The female fish will make what is called a “redd” in the gravel or stones, creating a safe place to lay their eggs. They create a redd by beating their tail side to side while remaining stationary, clearing the stones away and making a sort of well or small hole. During spawning, the eggs are deposited into the redd and then covered over with the removed gravel to keep them safe and secure from both running currents and predators.

Typically, the eggs hatch in four to eight weeks, and the young fish are independent from day one. When sea run rainbow trout return to their homeland to spawn, the offspring remain in the river for usually around one year before returning to the ocean.

Recognizing a rainbow

rainbow troutAs the name suggests, these fish have striking coloration that make them easy to recognize. While no two rainbow trout are identical, and can in fact appear quite different, the distinctive pink stripe down each side is always present. This stripe runs right from the gills to the tail, and can appear thick or relatively narrow. The characteristic rainbow stripe is the best way to recognize these fish, as their appearance can differ significantly in other aspects. Some members of the species have dark spots, others have pale spots and tend to be more chrome colored rather than the deep silver that many expect when they think of a rainbow trout. The coloration of these fish differs greatly depending on their diet, their habitat, their health and also their genetics.

Rainbows for Sport

All across the world, these magnificent fish are sought after by fly fishermen who will go to great lengths to land the perfect rainbow. In the southern hemisphere, Australia and New Zealand offer world class lake and river trout fishing, and steelhead residing in the Pacific North West of the USA represent the best of what is on offer in the northern hemisphere. These fish are coveted for a number of reasons, in particular because of how much they fight when they are hooked. These fish are famous for leaping from the water in a manner that many people only associate with manner, and can be surprisingly challenging to finally net at the end of a long battle. For so many anglers, the pot of gold really can be found when you follow a rainbow.


I spend time between the love of my life (my wife), my digital agency, and trying to squeak in time for fly fishing when I can hide from responsibilities. If you want to strike up a conversation with me try subjects on: fly fishing, fly tying, cooking, photography, reading, camping or anything related to social media or marketing.