Being knowledgeable about the wild trout in Colorado you may catch is an important element of your success and overall enjoyment of the fly fishing experience.

It’s 2022. And when fly anglers are unable to get to the river, they are increasingly going for the next best thing: tuning into their favorite fly fishing YouTube channel of course!

In recent years, angling YouTubers have proliferated and produced amazing content – much to the delight of pencil-pushing fly fishermen everywhere. A few of my personal favorites are Wild Fly, Tight Loops, and the classic The New Fly Fisher. I’ve logged some serious time keeping up with these channels as I unwind after a long day at work and with the family. I’m thankful for the way they bring the river to me and for the opportunity to learn a few things along the way. One thing I have noticed in watching these videos of other people fishing is the angler’s ability to accurately identify the trout they have on the line – even after only getting a quick flash in the early stage of the battle.

“Another rainbow!”, they’ll call out. Or:

“Oh nice, a brookie!”

Identifying Wild Trout in Colorado

Nine times out of ten their identification is right and this is partly because they have caught so many fish in their lifetimes. They only need a quick glimpse to know exactly what’s on the line, long before it hits the net. The other reason they can do this so quickly is they know beforehand what species are found in the given stream they are fishing that day.  In many cases, they are targeting that specific species, keeping in mind the season, weather patterns, water temperature, and other relevant variables that would affect their ability to successfully hook up with the species they are targeting. 

Many anglers on YouTube have the ability to quickly – and accurately – identify the wild trout they have on the line.

Being knowledgeable about the wild trout you will run into in Colorado is an important element of your success. Not only will understanding a bit about each species allow you to build better strategies on the river, but it will also help you be a better conversationist, and heck – it might make you sound like a pro on your YouTube channel! Let’s go over the three primary species of trout you are likely to run into on Colorado streams and understand a bit about their behavior throughout the year.

Cutthroat Trout (Oncorhynchus clarkii)

These gorgeous trout are actually the only native trout to the watersheds of Colorado. Hundreds of years ago, these are the only trout you could catch in Colorado. They can be identified by the reddish-orangish streak on the bottom of either side of the fish’s jaw. They usually have black spots well below the midsection of the trout’s side and a multitude of smaller spots on the tail fin. Colorado Parks & Wildlife officially recognizes three subspecies of cutthroat: the Greenback Cutthroat, Rio Grande Cutthroat, and Colorado River Cutthroat. All Cutthroat in Colorado spawn during the spring to the summer season when water temperatures begin to warm above 43°F. Fishing for cutthroat – especially in their native streams can be a great joy as they are usually aggressive and will eagerly take a well-presented dry fly. Many Colorado anglers will work towards achieving a Colorado Cutthroat Slam (or a Cut Slam for short) which involves the angler landing all three species of cutthroat – a worthy goal!

Brown Trout (Salmo trutta)

While not native to Colorado this European fish was introduced to Colorado in the late 1800s and can now be found across the state in virtually every major fishery. These deft predators are known for their keen wit and ability to grow to monster sizes. The state record brown was caught in Roaring Judy Ponds in Gunnison County back in 1988 and was a whopping 30.5 pounds – compare that to the state record native Cutthroat at 16 pounds caught in Twin Lakes in Lake County. Brown trout can be easily identified by their trademark golden yellow belly, as well as their golden brown-to-silver dorsal area as well as their silver-haloed red spots. Brown trout spawn in the fall when temperatures finally drop to 44°F. In Colorado, brown trout can be targeted year round but are the most fun in the spring when they are hungrily emerging from the long, food-scarce, and frigid winters. Anglers enjoy finding the gnarliest streamer pattern in their box to target those bigger brown trout that tend to feast most aggressively during the last few moments of light in the day or after a long warm rain.

First introduced to Colorado in the late 1800s, brown trout can now be found in virtually every major fishery in the state. 

Rainbow Trout (Oncorhynchus mykiss)

Another non-native species that can be found just about everywhere across the state is the Rainbow Trout. This industrious fish is the primary fish grown and stocked by the millions by Colorado Fish & Wildlife throughout the year. Like the native cutthroat, they spawn in the spring as water temperatures warm up and can be easily identified by their trademark pink band across their side. 

An Important Note About Spawning

In fly fishing, it is generally frowned upon to target trout – even the invasive species – in the middle of their spawn. Avoid casting to fish acting unusually in shallow gravel beds during their respective spawning season. Be on the lookout for the shallow depressions female trout make with their tails. These are carefully guarded before and after being fertilized by the triumphant male. Protecting these fish during their spawn will ensure there are plenty of fish – of every species – for you to enjoy, catch, and identify for years to come!