Breaking down fly fishing for trout through basic deduction.

I recently fished with a friend on a local stream. He worked the stream very quickly, bouncing from one section to another. A quick cast and drift then on his way to another spot. It occurred to me that covering a lot of water has its place and time. I have written about this before. Contrastingly, working a section slowly and meticulously also has its application.

So what makes sense and when? When is the appropriate time to use these contrasting methods? Let’s step back and look at some basic code cracking factors. By code cracking I’m using the analogy of cracking a safe by guessing the lock’s code combination. This starts with making a hypothesis about the situation at hand. Fine, but how to start?

Break your situation at a basic component necessary to all fishing:


Time is probably the most critical component to successful fishing. Time of year and day most often dictate what the fish are typically doing. During the winter months in Pennsylvania it’s fair to say that it’s cold relative to the rest of the year. This means more than often the fish have slowed down. Besides the temperature affecting them biologically for example slowing metabolism, the food source has slowed as well. For the angler this means slowing down with them. You are not going to have much success by aggressively stripping a streamer though the top part of the water column in December. In this example, if you are bent on streamer fishing, a slow dead drift along the bottom will produce much better results.

Easy right. It’s a good start but not so fast.

Time also dictates where the fish congregate. Let’s stick with the winter season example. During the winter months, you will find congregations of brown trout in slow water, namely deeper pools. They have completed their spawning by late November and dropped back to deeper water for refuge.

You see we now deduce location through time at the macro-level. Let’s look at time on a micro-level; time of day. Again using the winter season example, based on the macro time component, we now know to locate deeper slower water. But would the crack of dawn make sense? Of course not, we need the sun to help warm things up. So, generally speaking, the best time in winter is between 12:00 and 3:00. Great so we now know when to go and where so what’s remaining?


Let’s build on what we have so far. Since we determined location on a macro and micro level. We can deduce what food sources will be available. Of course this varies from stream to stream and specific location on the stream, but it’s safe to make some general assumptions. Most feeding activity will be below the surface in the form of nymphs, excluding the special exception of the marvelous winter midge. We could speculate and assume that smaller flies would work best but that is would be a misconception and beyond the scope of this article. It is best to study the food activity and historical evidence to best determine what to use at any given point in time on the water at hand. Based upon our previous code cracking efforts, we can make with reasonable conviction that the food will be active sub-surface. Next, what’s the water doing?

Flow and Turbidity

Staying with our winter example, typically the water flows are low and clear. Of course there are many exceptions to this rule. Snowmelt, or rain can cause high water events that change the code. If it is a snow melt event then prepare for some tough fishing. The shot of cold water caused by the melting snow will put the fish in to lethargic mode; even more than they already are in the winter. If it’s a high water event from rain or high water from a tail-water release then this can actually be to your favor. Maybe the initial melt was a few days ago and the water is high but warmer than the original blast. Then ask how clear is the water and how fast is it flowing. As a common rule, the cloudier and faster the water the larger and darker the fly you will want to use. If we use the sequence of deduction listed in this article, then it may be as simple as using a larger version of a Pheasant Tail nymph with a touch of flash and weighted appropriately. Contrastingly, low and clear water conditions may require the opposite in the form of a long fine leader with a curly-Q indicator.

Other Variables

I probably should have used a card playing analogy, because I want to call this next component the Wild Card but I will remain consistent and call it Retina Scan and other mid-boggling code-cracking variances. What is going to throw much of this out the window? Or better yet, what is an additional level to cracking the code? Many things to many to list but a smattering include: angling pressure, hatchery vs. wild species, tail-water releases, stream erosion, and bio-diversity. When looking for that perfect code cracker, don’t forget the over-looked and under-appreciated components. With our winter example, if this is a tail-water that gets tons of angling pressure, in low water conditions, and the trout are wild then a Zebra midge tied on a 5 to 7X tippet may be the perfect combination to bring fish to hand; a.k.a., Lightly sand your fingertips. If the tail-water is chocked full of pale rainbow stockers, then throw on a egg pattern and let the games begin.

Just as a rookie safe cracker, using the basic deductions will provide plenty of rewarding fishing experiences. As you become better, more and more safes will not stand a chance to your brilliant skills and expertise.

Beginner’s Guide to Fly Fishing for Trout

One thought on “Breaking down fly fishing for trout through basic deduction.”

  1. Leo,

    Another great addition! Thank you.

    I believe your article on “Logical Deduction” to be a benefit to both new and well seasoned anglers – it is a systematic approach for beginners to use to further their enjoyment and a great refresher of the thought processes used to increase one’s odds of success!

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