Cutthroat Trout Fishing Guide
Freshwater · Water temp 44–63°F (ideal 56°F)
Quick Facts
- Identifying mark
- Red-orange slash under the lower jaw, present on every subspecies
- State fish of
- Idaho, Wyoming, Montana, Utah, Nevada, Colorado and New Mexico, by subspecies
- Typical size
- 10-16 inches in small streams; lake fish and Lahontan strain run far larger
- Range
- Interior West and the Pacific slope, from southeast Alaska to New Mexico
- Habitat
- Cold freestone streams, tailwaters, alpine and desert lakes
- Forage
- Grasshoppers, ants, beetles, mayflies, stoneflies
- Tackle
- 4 to 6 weight fly rod, 9 ft, 4X to 6X tippet
Overview
Cutthroat trout are the native trout of the interior American West, and the only trout in this guide whose range is genuinely regional rather than national. They are the state fish of six states, more than any trout except brook, and the subspecies map reads like a gazetteer of western water: westslope in Montana and Idaho, Yellowstone through the Snake and Yellowstone drainages, Bonneville in Utah, Lahontan in Nevada, greenback in Colorado, Rio Grande in New Mexico, and coastal cutthroat down the Pacific slope from southeast Alaska into northern California. The red-orange slash under the jaw that gives them their name is the one feature they all share.
Cutthroat hold from about 44 to 63 degrees Fahrenheit, with an ideal near 56 degrees. The temptation is to file them as a colder rainbow trout, and the research says that is the wrong model. When westslope cutthroat and rainbow were raised side by side across the same temperature range, their optimum growth temperatures came out half a degree Celsius apart, which is to say the same. What separated them was the ceiling: the upper lethal limit for cutthroat sat almost five degrees Celsius below rainbow's. The two fish want identical water, and only one of them can stay when it warms. Above about 68 degrees a river stops being cutthroat water and starts being rainbow water, which is the mechanism behind a century of cutthroat losing ground to introduced rainbow across the West.
The practical consequence for an angler is a fishery that runs on a different clock than the rest of this guide. A snowmelt freestone stream at 8,000 feet sits in the 40s at dawn, below the temperature at which either the insects or the fish do much, and does not reach its own optimum until late morning. Cutthroat therefore feed hardest through the middle of the day, which inverts the dawn and dusk advice that applies to almost every other species here. The old counsel on the Lamar and on Slough Creek, that there is no reason to be on the water before nine, is not laziness. It is the water temperature.
Optimal Conditions
| water Temp | 44-63°F, ideal 56°F |
| air Temp | 35-75°F |
| wind | 0-10 mph ideal, tolerate up to 20 mph; calm water matters for dry-fly presentation |
| pressure | Moderate sensitivity; recovers quickly, within half a day |
| light | Medium. The midday window is the strongest, which is unusual for a trout |
| best Seasons | Late summer into fall (August-October), then early spring before runoff |
Seasonal Patterns
spring
A short, good window before the snow melts. Water in the 40s in March and April brings fish onto seams and into lower-river runs, and nymphs and small streamers move them. It ends abruptly: once runoff starts, most cutthroat rivers in the West are unfishable for weeks, and the streamflow factor in this forecast will show it long before the calendar does.
summer
Spawning happens on the back of runoff, in May and June, and fish are distracted and rivers are high. From July the season proper begins. Post-runoff water drops and clears, terrestrials come off the banks, and cutthroat move into riffles, pocket water and the mouths of cold tributaries. Watch the ceiling rather than the floor: once a river pushes past the low 60s the fish go looking for colder water, and by 68 degrees you are fishing for rainbow whether you meant to or not.
fall
The best of the year and the bigger of the two seasonal lifts we apply to this fish. August through October is hopper season, when cutthroat sit tight to grassy banks and eat anything large that lands badly. Cooling water pulls them back into the main current, and the willingness that makes this species famous is at its peak. Bright cold days with a bit of wind to knock terrestrials onto the water are as good as western trout fishing gets.
winter
Activity drops well below 40 degrees and the fishery mostly moves to tailwaters, where dam releases hold temperatures fishable when freestone rivers are locked up. Fish sit in slow deep pools and eat small midge patterns during the warmest hours of the afternoon. The midday preference that shapes the rest of the year gets sharper in winter rather than softer.
Best Times to Fish
dawn
The weakest window of the day for this species, which is the reverse of nearly every other fish in this guide. High-country water is at its coldest just after first light, often below the range where insects hatch or trout feed with any conviction. Worth fishing on a warm low-elevation tailwater, and worth sleeping through on a mountain freestone.
midday
The peak. As the sun works on a cold river through the morning, water temperature climbs toward the range where hatches happen and cutthroat feed, and the best hours run from late morning through mid-afternoon. Terrestrial fishing in particular is a midday game, because grasshoppers do not move until the day warms.
dusk
A secondary window that improves as summer goes on and the water holds its warmth later. On hot late-summer days the evening can beat the middle of the day, since the river has had time to warm and the light is off the water. In spring and autumn the evening cools too fast to matter much.
night
Effectively no fishery. Cutthroat are drift feeders that hunt by sight, and unlike brown trout they do not develop a meaningful nocturnal habit. Most of their water is also closed to night fishing, and cold air drainage in mountain valleys makes it uncomfortable besides.
solunar
Moderate solunar sensitivity, and in practice hatch timing and water temperature swamp it on a trout stream. A major period landing in the middle of a warm afternoon is a good sign, but it will not rescue a river that is too cold or blown out.
Weather Response
Cutthroat handle fronts better than most species here and recover inside half a day. The problem after a front is not the pressure but the temperature: a cold night can pull a small stream back below its feeding range and delay the day's window by hours. Push your start time later rather than fishing harder.
Very good, and for a specific reason. Warming air lifts a cold river toward the range where insects emerge, so a warm front in spring or autumn can turn a slow river on within a day. The one exception is high summer, when additional warming pushes an already marginal river past the ceiling.
Settled warm weather in late summer produces the most reliable cutthroat fishing of the year: predictable afternoon terrestrial activity, clear low water, and fish sitting where you expect them. Long stable spells do make the water clear enough that approach and presentation start to matter more than fly choice.
Light rain is good, knocking terrestrials onto the water and taking the glare off the surface. Heavy or sustained rain is the risk in this country, because mountain drainages rise and colour fast, and a freestone river can go from perfect to unfishable in a few hours. Tailwaters are the fallback when that happens.
Proven Techniques
Foam Terrestrials and Attractor Dries
The signature cutthroat method and the reason many anglers travel west for them. A large foam hopper, ant or beetle pattern cast tight to a grassy bank in late summer draws a slow, deliberate, entirely visible rise. Cutthroat are the least selective trout in the West, which means an attractor pattern that no real insect resembles will often outfish a careful imitation.
Dry-Dropper
A buoyant dry fly with a beadhead nymph suspended 18 to 36 inches below covers both the surface and the drift in one cast. The standard rig for prospecting unfamiliar water, and especially effective in the pocket water and riffles cutthroat hold in through summer. The dry doubles as the strike indicator.
Nymphing Runs and Seams
Before runoff and again in winter, most cutthroat feeding happens subsurface. Dead-drift stonefly nymphs, pheasant tails and small midge patterns through runs and along current seams under an indicator. Getting the fly to the bottom matters more than the pattern, so adjust weight before changing flies.
Small Streamers
Sculpin and small baitfish patterns swung or stripped through deeper runs and undercut banks take the larger fish, particularly in spring and on overcast autumn days. Less central to cutthroat than to brown trout, but it is the way to find the biggest fish in a given piece of water.
Stillwater Chironomids
The high alpine lakes and the desert lakes hold some of the largest cutthroat anywhere, including the Lahontan strain in Nevada. Suspending chironomid pupae under an indicator over drop-offs and weed edges is the method, and it rewards patience over casting.
Cutthroat Trout vs Rainbow Trout
These two share water across the whole West, hybridise where they meet, and are often caught on the same day with the same fly. The difference that matters is not what they prefer. It is what they can survive.
| Cutthroat Trout | Rainbow Trout | |
|---|---|---|
| Preferred temperature | Ideal near 56 degrees | Ideal near 55 degrees, which is effectively the same |
| Upper limit | Struggles past the low 60s, done by about 68 | Comfortable several degrees higher, which is the whole story |
| Best time of day | Midday, because the water needs to warm first | Dawn and dusk, in the usual trout pattern |
| Selectivity | The least selective trout in the West; attractor patterns work | More selective, and rewards matching the hatch |
| Spawning | Spring, on the back of snowmelt, at 42 to 52 degrees | Spring, slightly earlier and at lower elevation |
| Where you find them | Headwaters and colder upstream reaches | Downstream, and moving further up as rivers warm |
Chasing the other one? Read the rainbow trout guide.
Cutthroat Trout Fishing Questions
What is the best time of day to catch cutthroat trout?
The middle of the day, which is the opposite of the advice for almost every other trout. High-elevation freestone streams sit in the 40s at first light, below the temperature at which insects hatch or trout feed with much conviction, and only reach their productive range by late morning. The strongest window runs from late morning through mid-afternoon, and terrestrial fishing in particular depends on it because grasshoppers do not move until the day warms. On a low-elevation tailwater the usual dawn and dusk pattern reasserts itself.
What water temperature is best for cutthroat trout?
Around 56 degrees Fahrenheit, in a band from roughly 44 to 63. That ideal comes from controlled growth trials on westslope cutthroat, which put their optimum at 13.6 degrees Celsius. The number worth remembering is not the optimum though, it is the ceiling. Cutthroat are in trouble by the mid 60s and effectively out of the picture by 68 degrees, where rainbow trout are still comfortable. If a river you know as cutthroat water is running warm, you are probably going to catch rainbow.
What is the difference between cutthroat and rainbow trout?
Look under the jaw: cutthroat carry a red-orange slash there and rainbow do not. Behaviourally the two want the same water, since their optimum growth temperatures are within half a degree Celsius of each other, but rainbow tolerate roughly five degrees Celsius more heat before it becomes lethal. That single difference explains why introduced rainbow have displaced cutthroat from the lower, warmer reaches of western rivers over the past century, pushing native populations into the coldest headwaters. Cutthroat are also markedly less selective and will take an attractor pattern that no real insect resembles.
Are there different kinds of cutthroat trout?
Yes, and which one you are fishing for depends entirely on where you stand. Westslope cutthroat hold Montana and northern Idaho, Yellowstone cutthroat the Yellowstone and Snake drainages, Bonneville cutthroat Utah, Lahontan cutthroat the Nevada desert lakes, greenback cutthroat the Colorado Front Range, Rio Grande cutthroat northern New Mexico, and coastal cutthroat the Pacific slope from southeast Alaska into California. This forecast models the interior fish. The Lahontan strain is the notable exception, being adapted to alkaline desert lakes and tolerating both higher pH and warmer water than any of its relatives.
When do cutthroat trout spawn?
In spring, on a snowmelt clock, generally April into June and later still at high elevation. Spawning runs happen as water climbs through roughly 42 to 52 degrees Fahrenheit, and fish move into tributary streams to cut redds in gravel. This puts spawning right on top of runoff across much of the West, which is why May and June are the weakest stretch of the cutthroat calendar: the fish are distracted and the rivers are high and coloured. This is unlike brown trout, which spawn in autumn.
Why is fall the best season for cutthroat?
Three things line up. Runoff is long past, so rivers are low and clear and fish are easy to find. Grasshoppers, ants and beetles are at their peak abundance on the banks, and cutthroat are the trout most willing to eat a large, obvious terrestrial on the surface. And water temperatures come down off the summer ceiling into the range this fish actually wants, pulling it back into the main current from whatever cold refuge it was using. August through October is the peak, and our scoring reflects it as the bigger of the two seasonal lifts we apply.
Best Months for Cutthroat Trout
These are the months our scoring lifts cutthroat trout activity for pre-spawn or autumn feeding. Open one for that month's calendar.
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