The strike came at the end of a day’s fishing, just before the driftboat reached the take-out. Floating the “B” section of Utah’s Green River below Flaming Gorge Reservoir in Utah, it had already been a memorable day. I’d landed several rainbow and brown trout, not to mention two feisty mountain whitefish. A small percentage of anglers manage a three-species day on the Green. I was about to add a fourth.

With a mighty tug, the finned charger on the end of my tippet ran for deeper water, pulling yards of line from the reel. At the end of the surge it turned. For an instant, I glimpsed a long, flaxen form swerving in the current. “It’s a big brown,” I announced to my boat-mates with a smug smile.

It was big. And brown, sort of. Brought to net the fish proved to be a very large flannelmouth sucker (catostomus lattipinnus), only the second specimen of its kind my guide had seen in a decade of angling on the Green River.

A curious fish with large, downturned lips and a hulking upper body narrowing dramatically to a slender tail, the flannelmouth sucker is native to the Colorado River basin in the southwestern United States, ranging as far north as southern Wyoming. It is a bottom-dwelling (benthic) species that feeds primarily on algae and plant matter, but also consumes invertebrates. Although not technically endangered, flannelmouth sucker populations are threatened in many places by stream flow alterations, habitat loss and competition from non-native fishes.