Greenback Cutthroat Trout
Colorado's state fish and the easternmost cutthroat subspecies, the greenback evolved in isolation in the South Platte drainage after Ice Age ancestors crossed the Continental Divide.
It nearly blinked out — today it occupies less than 1% of its historic range, all of it on permitted catch-and-release water above 9,000 feet.
Also known as Greenback, Colorado State Fish
- Spots are the giveaway — the largest and most numerous of any cutthroat subspecies, bold and black, clustered heavily toward the tail.
- Crimson slash marks under each side of the lower jaw clinch the ID; spawning males flush blood-red along the belly and are reported to carry the most vivid colors of any cutthroat.
- Olive back fading to yellow flanks — despite the name, not noticeably green; elongated body with the highest lateral-line scale counts of Colorado's three native cutthroats.
- Most headwater adults are 6–12 inches and max out near 10 at extreme altitude; lake fish occasionally reach 15–18 inches, with a maximum recorded length of 18 inches.
What to know
Habitat Distribution
- Native only to the South Platte drainage of eastern Colorado and a small piece of southeastern Wyoming, with historic stream habitat above 5,900 feet east of the Continental Divide.
- Wild populations now live exclusively in clear, cold, well-oxygenated headwater streams and alpine lakes between roughly 7,000 and 11,000 feet on the east slope of the Rockies.
- Every surviving population sits above a natural or man-made barrier that locks out brook and brown trout — without that isolation, greenbacks are typically displaced within five years.
- The bulk of accessible water is on federal land — Rocky Mountain National Park, Arapaho, Roosevelt, and San Isabel National Forests — with active restoration expanding the map in the Poudre headwaters and Clear Creek drainage.
Specific Spots
- Adults tuck under overhanging branches, undercut banks, and into eddies behind boulders where overhead cover meets a feeding lane; juveniles stay out in shallow, open backwater margins.
- Plunge pools and pocket water below short drops put the fish in soft seams behind boulders watching the drift line above — the most reliable lie in any headwater reach.
- Pools deep enough not to freeze through winter hold the largest fish in a given stretch, since freeze-out is a real mortality bottleneck at altitude.
- On lakes, work inlets, outlets, and shoreline stretches with visible bug activity — open basin water rarely produces.
Greenback Cutthroat Trout FAQ
Answers from onWater's species guide.
What are the best lures and bait for Greenback Cutthroat Trout?
Where conventional gear is even legal, downsized inline spinners and compact spoons in trout sizes are the productive categories in both small streams and high lakes, but legal greenback water that allows them is genuinely rare, and worms or salmon eggs are off the table on virtually all of it.
What flies work for Greenback Cutthroat Trout?
Pocket water and plunge pools above 9,000 feet reward a high-floating searching dry, Royal Wulff, Adams, Elk Hair Caddis (a caddis-adult imitation), drifted along the seam behind a boulder. The fish's willingness at altitude is the whole reason these patterns work.
What do Greenback Cutthroat Trout eat?
Mayflies, stoneflies, and caddisflies, both as drifting nymphs and emerging adults, make up the core diet, so a Hare's Ear or Pheasant Tail (mayfly-nymph imitations) and an Elk Hair Caddis (caddis adult) cover most stream situations.
Where do Greenback Cutthroat Trout live?
Native only to the South Platte drainage of eastern Colorado and a small piece of southeastern Wyoming, with historic stream habitat above 5,900 feet east of the Continental Divide.
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