Fish Behavior | Fly Fishing Insider Podcast

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Fly fishing is more than just a hobby; it's akin to an art form where a deep understanding of fish behavior plays a crucial role. For the seasoned angler, diving into the intricacies of how fish act and react in their environment not only enriches the fishing experience but also increases the chances of success. Fish behavior is easy to observe and learn from so let's take a look at why and how.



Observing fish in their natural habitat is the first step toward understanding their behavior. This involves spending time watching how fish in streams respond to changes in light, water flow, or the presence of predators. It's important to note the subtleties of fish behavior, like how a fish positions itself in the current, its reactions to surface activity, or its retreat to safety. Key aspects to observe include their feeding patterns - whether they are actively feeding or holding steady - and how environmental factors like weather, water clarity, and temperature impact their behavior.


The way a fish moves and where it positions itself in the water can reveal a lot about its current state. Fish behavior that is swaying side to side is often actively feeding fish, especially in streams, as they target drifting nymphs or emergers. On the other hand, sudden, short movements usually indicate a defensive fish behavior or a reaction to potential threats. Fish near the bottom are typically resting or in a less active feeding state, while those at mid-water or near the surface are more likely to be actively feeding, especially during a hatch.



Understanding these behaviors aids in selecting the right fly and its presentation. Surface feeding calls for dry flies or emergers, while for fish holding deeper, nymphs or streamers might be more suitable. The presentation of the fly is crucial. Presenting should be done with stealth and precision to avoid startling the fish. The fly should mimic the natural drift of real insects in the current, as fish are highly sensitive to unnatural movements. It’s such a critical aspect I’ve created a cheat sheet and article all around the notion of presentation called, Formula for Systematizing Your Cast for a Perfect Drift.


An experienced angler also knows how to read the water and understand how weather patterns affect fish behavior. Fish often prefer areas with slower currents, like behind rocks or in deeper pools. Weather conditions also play a significant role. For instance, overcast days might see more surface activity, while bright sunny days could mean fish holding deeper. Temperature drops can change position. For example, I’m headed to the Green River in Utah to do so fishing. I anticipate being able to throw streamers. It’s January and I love fishing this style in the winter. However, we are expecting a temperature change where it drops from the mid-20s to the single digits. Because the river is a tailwater and the dam releases water from the bottom the water temperature shouldn’t change from the air temperature much but it will likely have an effect. I suspect that I will need to fish slower and deeper than I normally do. 



Fish behavior changes with the seasons, necessitating different strategies. Spring might bring active surface feeding during hatches, necessitating the use of emergers or dry flies. In summer, the focus should be on early morning or late evening when fish are more active. During fall, streamers can be effective as fish become more aggressive before spawning. A prime example in fish behavior related to seasons is terrestrials. Few heads out in the dead of winter to fish hoppers or ants. It’s not because the patterns aren’t good or that fish don’t eat terrestrials it is because they are all in hibernation all winter and are not a typical food source so we intrinsically know that the fish behave there. I’ll say it again, you need to read the book Seasons for Trout it does an absolutely excellent job of richly defining the season, how trout feed, and what to think about. 


Finally, thinking like a fish means understanding the prey species in the fishing environment and how fish might target them. This involves knowing what fish feed on in each season and matching the fly accordingly. Larger fish might prefer a stealthy ambush approach, so positioning the fly to mimic vulnerable prey can be effective.


Understanding fish behavior is a continuous learning process that significantly impacts fly fishing success and enjoyment. By combining careful observation, an understanding of environmental factors, and a thoughtful approach to fly selection and presentation, anglers can elevate their fishing experience to new heights.
My suggestion is that you pick a day with a friend for a walk. Go to the river or local water and leave the rod at home. Walk the river and see how many fish you can spot. When you do have a fish in your sight, take a minute to observe its behavior. What is it doing, is it feeding, is it resting, is it defending its territory?  All things to consider, look for, and remember. Then start applying those same tactics when you go out. Lastly, keep in mind that fish are habitual, so they will likely be in the same zone when you return with your rod. Be ready to observe again and test your observations. 

If you like this you'll like the article "OSSCP Fly Selection Formula for Success" 

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 Christian Bacasa, Host of the Fly Fishing Insider Podcast

By Christian Bacasa
Host of the Fly Fishing Insider Podcast
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