Since there is no traditional casting involved, a tapered leader will actually be a detriment. The leader is made out of a length of monofilament or fluorocarbon of a sufficient pound test, based on size of fish likely to be caught and the type of river bottom. You must use leader material that is strong enough not to break when you hook the bottom or a rock.
Original Leader Construction:
Start with some sort of Hi-Vis Sighter connected to the fly line like a Czech Nymphing Hi-Vis Indicator Braided Butt Section or a section of Jan Siman Bi-Colored Indicator material.
You will then use a 40 to 50 inch section of level tippet in 4, 5 or 6X depending on the size of fish you are pursuing. Typically, 5X is the perfect size for most situations.
Next, take a 28 to 30 inch section of the same size tippet material used in the butt section and attach it to the butt section. This is where you also form the dropper tag so you will want a 6 to 8 inch section of butt or “parent” material when tying the knot. You can use several knots to attach this section of tippet to the “parent” line or butt section but the strongest one we have found it the Orvis Tippet Knot
The overall length of the Original Czech Nymphing Leader should be ¾ the length of the rod you are using. The basic principal of the leader being this long is, after you hook a fish and have played it, you can raise your rod and land the fish without having to shorten the line (stripping in) If you feel the leader is too long, you can shorten it by cutting some off of the top section and re-attach it to the Hi-Vis indicator (if you are using one) or the end of the fly line.
Hybrid Czech Nymphing Leader:
With the evolution of Czech Nymphing here in the US, a lot of competition anglers have developed a leader that is more universal when it comes to covering water. The biggest pain with the Original Czech Nymphing Leader is that you can effectively fish right under the rod tip or slightly out but trying to reach that run across the river is a real pain as too much of the fly line comes into play which introduces too much slack and drag in the system.
This is where the Hybrid Czech Nymphing Leader comes into play as you can pull the butt section of the leader into the rod guides and fish up close and then reach out and touch those prime lies on the other side of that heavy run effectively as you are not constantly fighting to keep the fly line off of the water. This is a more dynamic system that combines the benefits of the level tippet of the Czech System with the long line benefits of the Spanish System.
How to Construct a Hybrid Czech Nymphing Leader:
Start with a 4 to 8 foot section of 20lb mono that is relatively stiff. I prefer the 20lb Stren – Clear Blue Transparent mono which is super stiff and extremely easy to see.
Next, attach a Hi-Vis Sighter like Jan Siman Bi-Colored Indicator material to the 20lb Stren.
From the Sighter, you construct the rest of the leader just like you would the Original Czech Nymphing leader including the dropper tag.
It is not uncommon to fish with the butt section in the rod guides when working up close, which is why we use such a stiff/heavy butt section. If you use mono that is too small or supple, it will wrap around the rod guides of the tip-top and break the rod when setting the hook.
Fly Placement on both the Original and Hybrid Czech leaders:
On a two fly rig, the heaviest fly will go on the bottom or point position. This will help get the flies down and run correctly when bouncing across the bottom.
When fishing, make sure that if you hook the bottom to check the flies and remove any weeds or moss from the hook. Also check the hook point for damage. A hook hone is an invaluable tool when Czech nymphing because you will need to at some point re-sharpen the hooks.
If you are constantly catching the bottom, change the point fly to a lighter one on and then adjust the top. You can also play with your rod angles to achieve the proper drift. If fishing shallow water you can start with a higher rod tip and then began to lower it once you get into deeper water. This is especially effective when fishing drop-offs.
Watch the sighter like a hawk!!! The sighter is telling you what the flies are doing, not if a fish has eaten your flies. If you have the proper tension on the leader by maintaining a 45-degree angle between the leader and the rod tip, strikes should not be a problem to detect. If there is too much slack in the system (line/leader is forming a lazy “J”), you will not feel the bottom or strikes and begin to rely on the sighter as an indicator which will casue you to miss a lot of fish!!!