No one truly knows why steelhead take flies. Like salmon, as soon as steelhead get in fresh water they stop actively feeding and simply rely upon fatty tissue storage to make it up the stream, spawn, after that go back to the ocean where they will stuff themselves and also make up for the long quickly in the fresh water. So it's type of frustrating that we fish using replicas of bugs and lure fish that they don't also consume in the sea yet are respected to the rivers.
The majority of us come from a trout angling background as well as are used to fish behaving in a rather predictable means. If there is a caddis hatch taking place as well as you can literally see trout proactively feeding for caddis there is a likelihood that if you make use of a pattern mimicing a caddis you're going to catch a trout. There is a direct as well as evident connection between just what fish are preying on and just what will offer you the most effective opportunity for success.