What Does a Fish See?

When it comes to fly tying the discussion/debate around what is important in the eyes of a fish is likely endless. Is the fly imitating a food source or is it simply an attractor? If imitating, what of the color, size, behaviour and so on and so on. We make decisions on what we observe, what has worked in the past, what our gut tells us, or maybe what tying material we have available at the time. At the end of the day - its pretty hard to say with certainty what will appeal to a fish. And if by chance we figure it out one day - the next it will be completely different.I am not much of a fly tier but I appreciate that many people have a much deeper insight into these things. However this fall I was struck by the most basic aspects of a fly pattern - its shape. A couple months ago I decided to tie a wooly bugger variant using some brown krystal flash hackle I had in my tying material. I'm not sure there was much objectivity in the decision - other than in the past, at this time of year I have had success fishing patterns like a Mrs. Simpson or a brown woolly bugger with a bit of flash in the tail.On a couple of occasions this fall the pattern has proven to be my go to pattern but what struck me as I fished it was the shape of the fly when wet. The messy hackle folded back to form a sleek minnow shaped body with a bit of sparkle. Based on the fish it caught, I guess it made a good impression although I don't have any actual statements from fish as to what they thought it was when they chowed down.