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Thermocline Effects On Catfishing



I have had a number of questions in recent weeks about where I am fishing and what techniques I am using to catch catfish this time of year, and many questions about what depths to fish, so I wanted to take an opportunity to cover thermocline and how it effects catfishing.

I am going to hit the highlights of the thermocline and it’s effects on catfishing in this article, and went into greater detail in the video below, so make sure after you read this article you watch the video. If you are catfishing right now, and don’t know what a thermocline is, or don’t understand how it effects the catfishing, you need to read the entire article and then watch the video, when you are done, you need to go back and read it and watch the video again.

This information can help make or break your summer fishing.

If you are not already signed up for the newsletter, you need to make sure you do so now! In the next few days I will be adding some additional information and videos that will not be available on the main website and will only be available to newsletter subscribers, and no, you won’t be able to find the videos on youtube either.

If you have been reading my articles here on Learn To Catch Catfish very long you probably know that I live in Texas. If you have never been to Texas, it is hot here, and I mean REALLY hot. I’m a native Texan and everyone always tells people when they move to Texas that you get used to it, but YOU DON’T, you just cope. Now is the time of year when you really need to play it safe, like I covered in stay safe for summer fishing.

Fishing for catfish in the summer can be very productive if you know what to look for and how the weather and water temperature effects the catfish, but if you don’t have a good understanding of it, it can be devastating to your catfishing.

In the past few months I have been limiting out the vast majority of my clients with channel catfish in a very short amount of time (25 channel catfish per person with as many as 5 people on the boat). We typically can catch these limits in a couple of hours if all goes well but I never fish more than 4 hours on a trip during this time of year.

The primary reason for this is by 9:00 in the morning it feels like you are fishing on the sun. It’s brutal.

There is a long scientific explanation for what happens with a thermocline. My father is a physics teacher and I could probably throw a video camera in front of him and let him start covering the scientific explanations and cause of thermocline and I am sure he could probably talk for hours but for time sake I won’t. Plus, we would probably all be completely lost in a firestorm of scientific jargon, so I am going to water it down and bit and give you the nuts and bolts of the thermocline and will then move on to how it effects your catfishing (or any fishing for that matter).

On to the thermocline….. and again, be sure to watch the video below, I will go into much greater detail!

Some Basic Thermocline FAQ:

What is it?
A thin band of water that that develops in the water column when the water surface temperature gets really warm, causing the upper part of the water column to be significantly warmer then the middle and lower part of the water column.

What water bodies have thermoclines.
Typically water bodies that sit relatively still lake lakes, reservoirs and even larger deeper ponds. Rivers or bodies of water that have constant moving water don’t develop a thermocline.

When does it develop

Generally you can start to see the effects when the water temperatures start to reach the mid to high 70’s. I have first noticed at with water temperatures as low as about seventy degrees before and  have also had some instances where I have not been able to clearly identify it until the water reached 78 degrees. The warmer the water gets the easier it is to identify the thermocline.

At what depth does it develop?

Generally I see the thermocline at about 22 to 23 feet deep, but have seen it deeper once or twice.

Will catfish feed below it?
Yes, catfish can go below the thermocline into the “dead zone” to feed but they cannot stay there, which makes targeting catfish there difficult. Some people have success jug fishing for catfish below the thermocline but the fish will die there very quickly.

How do I find it on my lake or reservoir

Use your graph. Any higher end graph with a high pixel rating will work (I use the Lowrance LCX-15MT). Look in deeper water around between 20 to 25 feet, paying close attention to that 22-23 foot range. Increase the power on your graph if you have that option, and increase the sensitivity.
You will see two things when you do this:
  • You will notice that there is a portion of the water with no, or very few fish below it.
  • When you increase the power/sensitivity enough you will start to get a lot of feedback on the graph, but you will also be able to see a distinct line in the water, and often times you can see two distinct lines, indicating the two major temperature changes.
Now, watch the videos below where I go into greater detail. This is a pretty lengthy topic so I had to break it up into several videos.

Thermocline Effects On Catfish and Fishing Part 1

Thermocline Effects On Catfish and Fishing Part 2

Thermocline Effects On Catfish and Fishing Part 3

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About Chad

Chad Ferguson is a professional catfish guide and founder of Learn To Catch Catfish. Click here to subscribe for more exclusive catfish fishing tips by email and then follow on Twitter or Google


  1. Landon Axt says:

    Very interesting, I have a question though. You said that lakes and ponds will develop a thermocline, but a river wont. The lakes I fish on are all man made that were dam’ed by Alabama power so during the day there is always a few turbines pulling water, but at night they don’t run the turbines. So during the day I could only assume that a thermocline would not develop, but what about at night when the turbines are not running?

    • I wanted to add to the question. Can a thermocline set up in a river sloo?

    • It is not something that could shut off night and day so it is there or it isn’t. I don’t have any first hand knowledge of a similar situation like yours so I can’t speak with any authority as to whether it would have a thermocline or not. There is an upcoming article and video on how to find the thermocline so you will be able to get out there yourself and tell!

    • It will either be there or it won’t, cannot come and go in that short of a time.

  2. Thanks so very much Chad, you are awesome.

  3. Yes, the thermocline is in the majority of waters step out into the slough or river & you will feel the diderence in the water temp as you wade deeper. Not stepping on any toes but I just took a class at my university on the thermoclines effects on rivers & its inhabitants. It was an easy 3 credit hours just taled about fishing for a semester! Your article was spot on! This was the same information as well as similar examples to what is being taught to biologists in college!

  4. Maybe I need to apply to be a professor of redneck-ology!

  5. Very good video. Thanks.

  6. Is the “dead zone” pretty much existent throughout the whole year? Or like the thermocline, does it only show up during the hotter times of the year?

    • Only during the warmers months. Watch the first video I explain it in detail there.

      • Thanks! Looks like I missed that part the first time I watched it. I’m gonna be doing some fishing this weekend on Lake Cypress Springs and will be using some techniques that I picked up from your website to help me catch fish!

  7. Great stuff man look forward to adding this to my bag of tricks out there… keep it coming

  8. James Greene says:

    Great explanation Chad. Very informative. I had always known of the difference in water temperatures the deeper you go, but I was always taught to catch Chanel Catfish you HAVE to fish on the bottom. :/ I just assumed they were bottom feeders all the time. What an eye opener!!!

    I cant wait to test this new-found knowledge out! So, a thermocline cannot be found in a pond or a large pond??? Hmmm…I’m not sure of the depth of the pond I frequent. I believe it to be in the area of 15-20 foot at its deepest level. I’ll have to test out bottom fishing and then back it off to 12-15 foot fishing and see what the difference in catching em;’ is at.

    Thanks again Chad for the eye opener!

  9. Landon, I too fish the Coosa River chain here in Alabama and reside on Lake Mitchell. There is still a thermocline in the warmer months in spite of whether or not the turbines are running. Although the water moves, the volume of water that is moved is not sufficent enough to affect the water temperature. There are depths throughout the different lakes on this chain that exceed 60ft. so therefore there is still a thermocline. It is usually noticed here on Mitchell by the end of May and as late as the end of June. Hope this helps!

  10. This is Mike Burns this is tell in all lake but I fish in the Missouri River
    and their isn’t no thermocle in the river I have found not tell in lakes. I know in lakes there is.
    God Bless you lets go fishing

  11. Grant Jones says:

    First of all, I am really enjoying the work you do with the web site. I have never caught a catfish. I hope that is going to change right away. I guess what I wanted to say about this subject of the thermocline, is I can see it easy on my electronics on the boat but I have a situation. I live about five miles away from a man made reservior that is only about 20-30 feet deep. It has banks that are slowly sloped into the water. Talking to the Fish and Game I was told that Lake Lowell (the one that I am talking about) is a hidden gem when it comes to catfish. Nobody really fishes it. They fish for Large Mouth Bass. I was told that fishing at a gravel rocky slope that goes out to a point is a real great place to fish for the Channel Cat. I was also told that using Crickets and Night Crawlers work good. I would like to know what you woud do? How would you approach with a boat? What bait would you use? and the whole experience. This will be my baptism into catfishing and I want it to be done right.
    Thanks again. I enjoy readi

    • Grant, That’s a lot of different questions. Why don’t you call the Catfishing Radio hotline at 817-381-5604 and leave a message with your questions and we will try to cover them in a future episode of catfishing radio!

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