How Deep to Fish
By far the most common mistake I see offshore anglers make is fishing in the wrong water depth, whether that's too shallow or too deep. In this blog, I am going to explain how to determine the correct depth of water you should be fishing in your lake.
The first and most accurate way to determine how deep you should be fishing offshore is by looking at how deep the bait fish are setting up on your fishery. Bait fish is kind of a catch all term for the food that the bass are feeding on.
For example, on a lot of highland and lowland reservoirs, the primary forage is going to be either gizzard shad, thread-fin shad or blueback herring, however you might be dealing with more panfish like perch or bluegill and that's the bait fish that the bass are feeding on. There are other types of bait fish out there as well. It's going to vary lake by lake, but in general, you should be able to find a type of bait fish that you can see on your fish finder.
In this image, you'll see a school of bait fish on the left and a school of bass on the right. Even though the bait fish are suspended over deeper water, they're in the exact same depth of water as the bass during that 10 to 15 foot zone.
In general, the bait fish are going to set up in the same depth as the bass. The other way to think about it is that the bass are going to be in the same depth as the bait fish because the bass have to be where the bait fish are since they need to eat to survive. Therefore, if those bait fish were setting up, let's say in 30 feet of water, those baits have to be down there because that's where their food source is and they're going to be in the exact same depth of water as the bait.
In the image bellow, the baitfish are on the right side of the screen and the bass are on the left side of the screen. They're in the exact same level in the water column. The bait fish are still in the exact same depth of water as those baits. What those baits are doing is waiting behind those rocks for those bait fish to swim over the rocks so they can ambush them. They're set up in ambush mode. You can see those bass positioning themselves behind an object waiting for bait fish to come over to the top of those rocks so they can eat them.
For those anglers who don't have a lot of shad in their fishery and have some fish like perch or bluegill, you can identify the depth of bait fish by where they bed in the form of bluegill beds. Here's a side imaging image of some bluegill beds, they're set up in 10 to 15 feet of water. This was taken in the middle of the summer time when those bluegill were actually in those beds laying their eggs.
During the summer, bream and perch will lay their eggs in every full moon and new moon throughout the entire summer. If you find those bluegill beds in 10 to 15 feet of water, you can be confident that those baths are also going to be set up in that 10 to 15 foot zone because they need to be in that zone to eat the baitfish.
There is one big exception to the rules I just laid out, and that's when you can't see the forage on your fish finder, either down imaging your side imaging. This happens when bass are feeding on crawfish, gobies, or sculpin because these types of bait fish will sit at the bottom of the rocks and are invisible on the fish finder. One thing we do know about these types of forage is that they like to set up around rocky areas in the bottom. This means you can graph around with your sight imaging, down imaging and 2D sonar to identify rock piles and rocky spots. Then you have to use a general rule of thumb to determine how deep is too deep to be fishing.
I've developed a basic rule of thumb using water clarity to determine how deep you should be fishing. If you can't see the bait fish on your fish finder then the rule of thumb is all based on how far you can see in the water. For example, in dirty water areas that have zero to one foot visibility, I find that the bass will set up at a maximum depth of about eight feet, so you don't want to fish any deeper than eight feet. That's the deepest you should look.
Next we have stained water with 2 to 3 feet of wire visibility. The way I get these wire visibility ranges is by tying on a white crank bait at the end of my fishing rod reel to the tip of the stick. When that bait disappears, I will pinch the rod and see if it disappeared. You don't need to be super specific here. This is a general rule of thumb. You are looking at less than 15 feet of water which is the maximum depth you want to fish.
Then you have clear water 45 foot visibility. This is where you do not want to fish. Anything deeper than 25 feet of water is not a good area. I have caught fish deeper than these maximum depths in all of these water visibilities, but that's definitely an exception to the rule.
For newer anglers, this is a great place to start, because you don't have a good basis to start from. I would follow these guidelines as closely as you can, because you will waste a lot of time if you try to fish deeper than these recommended levels in different water visibility. I would say 80-90% of the time these guidelines will work.
For newer anglers, this is a great place to start. I would follow these guidelines as closely as you can, because you will waste a lot of time if you try to fish deeper than these recommended levels in these different water visibility.
Now ultra clear water gets a little bit tricky. When you have 6 feet or more of visibility, the bass can go very deep. I have caught fish on Table Rock Lake as deep as 80 feet of water.
In the summer, this is a little bit easier, because you can use what's called the thermocline. The thermocline is something that you can use to determine the depth of the fish in any water visibility. It is this band of water that's formed between the top of the lake and the surface of the lake at the bottom of the lake.
The reason this band forms is because water is closer towards the surface or where the sky has more oxygen and is warmer. This is because the sun is hitting the surface of the water and the air is mixing with the water as the sky and the water meet. However, as you get deeper into the lake, you get further away from the oxygen in the air and further away from the sunshine. This causes the water to get colder and to have less oxygen, so you're going to have warm water sitting closer towards the surface and it's going to stay oxygenated. The water that's cold will sink down to the bottom resulting in less oxygen. The bass and bait fish need oxygen to survive, so they're going to be setting up above that thermocline wind just so they can have enough oxygen to be able to function and to continue living.
If you get below that thermocline, there's a lot less oxygen for the bass and they are not going to spend a lot of time down there just because it's not a great condition for them. However, they want to be near that thermocline because as you get further down to the water it gets cooler.
When it's really hot outside in the summer, they want to be in that cooler water, but they don't go below the thermocline because again, there's not enough oxygen. What this means is that the bass can be sitting up right on that thermocline or just above it for the majority of the summer which allows you to determine exactly where those fish are gonna be setting up offshore. Conveniently, you can identify a thermocline using the down imaging or to the view on your fish finder. All you have to do is idle into the middle of the lake and find deep water. Once you're out in the deepest part of your lake, crank up the sensitivity. You will notice a band of water in the middle that will form. This band is the thermocline.
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