Caught this one on a Lyle Special, a brown and yellow Yuk Bug of sorts--a Big Hole River fly designed by Lyle Reynolds of Melrose Montana. It's not clear pattern matters much. Anything big and fat that looks like it's alive will get an insepection. Channel Catfish are predators. They want to know about anything and everything drifting by.
Channel cats are often rumored to be in the deep fast roily water below an irrigation diversion, or at any natural place were a riffle drops off into a deeper run.
We also found them in slowly moving water two to three feet deep, but not at all off deep boiling banks on the strong side of the river. We did find them on the weak side of the river, in places were there was still a slow current and moderate depth. Weak side of the river places that taper off to nothing over exposed gravel produced almost nothing.
This one was the strongest fresh water fish I've ever encountered. Carp can be strong too but they don't last. This catfish nearly broke my six weight rod, and was still pulling line off the reel 1000 yards down river. If we hadn't been following in a boat I never would have landed him.