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Needs of a Trout

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  • Needs of a Trout

    I remember a phrase coined from A River Runs Through It, "only three more years to think like a trout" (hope that's word for word). This phrase was said by Brad Pitt after battling a big bow as he walked back upstream with the trout.

    This is a good phrase that has often stood out in my memory. Each time we go to a stream, we should mentally try to continue putting some pieces together like, why would a fish be holding here or just plain keeping track of where we caught fish and what they hit. By understanding some of the why's and where's in leads us to more fish and better fish. And the end result is a more enjoyable time on the stream.

    I will be the first to admit that I'm not a great river guide. The Toccoa and Hooch I give to the shops and their boats. I don't guide on any tailwaters...don't really have a reason too. But, on the rest of the streams in GA, understanding the "needs of a trout" will take you up several spots in your ranking (fishing abilities). This is some really simple stuff and after you finish reading you will more than likely agree and I hope it will help you while on the water.

    Needs of a trout: Simple...trout needs for survival are food, protection from the current, safety from predators, and comfort. Let's break these down and discuss by needs.


    There are four main food groups for trout. These are aquatic insects, terrestial insects, aquatic crustaceans, and other fish. Trout live by a basic principle (this is a must to survive) - they must spend less energy to take food than the energy spent to get the food. Or they simply perish. Trout are active according to the activity of insects (subsurface or surface feeding).

    Aquatic insects are mayflies, stoneflies, midges and caddis flies. Learn the life forms by checking under the rocks in the stream to see what are attaching themselves to the stone. You can use a small mesh screen downstream and rub up or stir up debris using your feet. The screen will catch items that you can match your flies to. Use these two ways to understand what is in the water for the trout to eat and what is the most common insect in the stream.

    Learn to match the insect to the hatching. Now, here in North GA on our streams, it is hard to say that we have to match a hatch. I usually say match the most common insect you see and present a good drift. This will work the majority of time. But, it is more important to understand where the trout are feeding (again subsurface or surface).


    Unlike fisherman, trout will tell no lies but they do hold in some different lies for different reasons. There are basically three types of lies: primary lie, feeding lie, and lie. A primary lie is where a trout can meet all or most of their needs (food, protection, safety and comfort). A feeding lie is where the trout will hold to feed on their choice food group (where two runs come together, riffles, head or tail of a pool, etc). A lie is where a trout will hold but does not meet all of their needs (under a log, in front of or behind a large boulder, deeper part of the stream, etc).

    Protection from current

    Have you ever spotted a trout and just watched as it held to the bottom of the stream? Many times the trout will barely move to maintain its position. A trout cannot survive by staying in the fast current the entire time so they position themselves based on the current and use items that obstruct the current to protect themselves from fatigue and the chance of perishing.

    Water hydraulics is something you need to understand as it deals with water in motion. By understanding what breaks up water just discovered where trout will hold for protection from the current.

    Safety from predators

    Ever noticed a trout you just spooked? If so, what was it doing? Getting out of dodge, right? Trout become accustomed to their surroundings. You, the angler, are not part of their surroundings.

    Trout has some of the sharpest vision around. They can almost see 360 degrees. They use their sharp vision to locate food and watch for predators. Once locating a predator, they move to safety (this can be under a rock or log, into deeper water, or just fleeing up or downstream).


    Each of our three species of trout here in North GA have a different comfort zone. Temperature wise, the Brown has the greatest with the Brookie having the least, and the Rainbow falls in between. Bear in mind that 70 degrees is just about the death mark for these fish. Although they can survive in this temperature for a short time, it often sparks a disease that can become a culprit for them.

    This is why it is important to keep up with stream temps. Have you ever noticed when fishing where a tributary comes into the main stream that you caught more fish there? Many times the trib is somewhat cooler water and trout will collect in this area due to the cooler water.

    Fish Hard! You Can Rest An Eternity.

    A North Georgia Fly Fishing Outfitter

  • #2
    `Probably also want to consider the most important one - dissolved oxygen.
    Last edited by Kent; 06-06-10, 06:45 PM.
    Fly Fish GA


    • #3
      Originally posted by Kent View Post
      `Probably also want to consider the most important one - dissolved oxygen.

      "I have been trying to make these threads a good read for anglers wanting to improve their skills and/or just wanting to learn some additional stuff about fishing for trout. I try hard to think the topic through and to not leave anything out pertaining to the subject. I hope to discuss each topic in length and provide detailed information that will help someone as they grow in this sport."

      I intentionally left "dissolved oxygen" out due to speaking about streams in North Georgia. A lack of adequate "dissolved oxygen" is rarely a problem in trout streams, unless the water is stagnant and/or high in pollutants. Reason this is not a problem in the vast majority of our streams is the fact that water cascades over rocks which in turn introduces (forces) air (oxygen) into the water. If I would have been speaking of tailwaters, rivers, hatcheries, trout farms and/or ponds, "dissolved oxygen" would more than likely have been included.

      Info for headwater blue liners...One thing that I may should have included is pH levels. Most trout can tolerate pH levels from low 4.5 to high 9.5. But in streams near the low end, acidic water limits or kills food production and this is why some of the brookies in the Smokies (and NE) have disappeared. As you may now know, after decades of being off limits and a restoration program in place, in 2006 the FS in the Smokies has opened up the majority of headwater streams to fishing for brookies. This was done after a 3 year study comparing the adult density was "no decline" between 8 streams opened to fishing and 8 streams closed to fishing.

      BTW, next thread to come will cover stream reading.

      Last edited by Reel'em In; 06-07-10, 07:56 AM. Reason: adding info
      Fish Hard! You Can Rest An Eternity.

      A North Georgia Fly Fishing Outfitter


      • #4
        Excellent post with some good info!! I'm looking forward to others!


        • #5

          Keep them coming. The information that you can pass on is invaluable.



          • #6
            Spot On!

            When I got back into trout fishing about 20 years ago, there were a few changes encountered during my ten year hiatus. One was graphite. Thought I had died and gone to heaven! The other was moving from Colorado to Georgia. My family bought me the old Orvis/Fish Hawk School way up in Rabun County and a fantastic teacher, Henry Williamson. I took away a lot from that course including "if you leave the river before you need a flashlight to find your way back to the truck you left too early", and "to catch trout think like a trout."

            Your inital post is an excellent summary for that second item. I have encouraged new anglers to not jump right in when they get to the stream, sit back, observe, and then start slow and close. When I had my cabin on Fightingtown, I would occasionally "go fishing" without taking the rod to avoid the distraction and find a place where I could get above the water to just observe the trout to see what they were doing. Fascinating. Spent hours doing that. Recently had a great opportunity near the end of the day to stand on a bridge over the Davidson watching three trout of three very distinct sizes in three very different lies. Spent over an hour just sitting there watching. Trust me, if you see a fish feeding, especially when the water is a little warm, they will not spend three calories swimming to eat a two calorie bug, your's or nature's. You have to get it exactly in their feeding lane.

            Thanks again! A great remedial read for me that I will put into use soon! --John Kies--