If you've been looking for a go-to nymph that flat-out catches fish, look no further. The Tungsten Jig Assassin is one of those rare patterns that checks every box — it sinks fast, has a lifelike profile, and triggers strikes from even the most finicky trout. In our latest fly tying tutorial, we walk you through every step of tying your very first Tungsten Jig Assassin, from threading your bobbin to finishing with UV resin.
Video by Sam Sheehy. Nice work Sam!
Why the Tungsten Jig Assassin Works
The Jig Assassin is built on a jig-style hook, which means the hook rides point-up in the water column — dramatically reducing snags on the bottom and increasing your hook-up ratio. Pair that with a heavy tungsten bead and you've got a fly that gets down to where trout are actually feeding, fast. The combination of a segmented biot body, a speckled Coq De Leon tail, and a soft CDC collar creates a profile that trout can't resist. It's buggy, it's realistic, and it moves beautifully in the current.
What You'll Need: The Full Materials List
All materials are available at FlyFishSD.com. Here's the complete breakdown:
Hook: Umpqua XC400 — A premium jig-style hook with a wide gap and reliable point. The barbless/narrow version makes catch-and-release easy on the fish and easy to remove from your net.
Bead: Hareline Bulk Tungsten Slotted Beads — The slotted design fits perfectly over the jig hook bend to keep the bead aligned and the hook riding correctly.
Thread: Semperfli Nano Silk 18/0 — Ultra-fine and incredibly strong, this thread lets you build a slim, clean body without adding bulk.
Tail: Hareline Coq De Leon — The signature speckled barring of Coq De Leon fibers mimics the legs and tails of real nymphs beautifully.
Wire Ribbing: Wapsi UTC Ultra Wire — Adds segmentation to the body and reinforces the biot wrap for durability.
Body: Nature's Spirit Turkey Biot Quill Pieces — Wrapped over the hook shank, biots create a smooth, segmented abdomen that looks incredibly lifelike.
Abdomen Case: Hareline Cinnamon Tip Turkey Tail Feathers — Pulled over the top of the abdomen to create the dark wing case that makes this pattern so distinctive.
Abdomen Dubbing: Wapsi Natural Fur Dubbing — Dark Hare's Mask — A touch of rough, natural dubbing adds texture and translucency to the thorax area, giving the fly a lifelike, buggy look.
Collar: Hareline Cul De Canard (CDC) — CDC fibers pulse and breathe in the water, simulating the movement of legs and emerging wings. This is what brings the fly to life.
UV Resin: Solarez Bone Dry Plus — Used to lock down the bead and finish the head with a clean, durable, professional-looking coat.
Step-by-Step Tying Instructions
Step 1 — Mount the Bead & Hook
Slide your slotted tungsten bead onto the Umpqua XC400 jig hook, with the larger slot seated against the hook bend. Secure the hook in your vise with the hook point facing up, as the jig eye is designed to fish that way. The bead should sit snug against the eye.
Step 2 — Start Your Thread
Start your Semperfli Nano Silk 18/0 thread just behind the bead and make several tight wraps to build a small thread dam that locks the bead in place. Run the thread in touching wraps all the way down to the bend of the hook. The ultra-fine diameter of the Nano Silk keeps the body slim from the very first wrap.
Step 3 — Tie In the Tail
Select 6–8 Coq De Leon fibers and align the tips. Tie them in at the bend of the hook so the tail extends roughly one hook gap in length. The speckled barring on the CDL fibers does a tremendous job of mimicking the segmented tails of natural nymphs. Trim the butt ends and return the thread to just above the bend.
Step 4 — Tie In the Wire Ribbing
Tie in a length of Ultra Wire at the bend of the hook, securing it along the underside of the shank with touching thread wraps back up to just behind the bead. This gives you a solid foundation for the biot body and keeps the wire from rolling.
Step 5 — Wrap the Biot Body
Tie in a single Turkey Biot Quill at the bend with the notch facing up (this produces the distinctive segmented edge along the body). Wrap the biot forward in tight, slightly overlapping turns toward the bead, then tie it off and trim the excess. The biot creates a smooth, tapered abdomen with natural segmentation built right in.
Step 6 — Counter-Wrap the Wire Rib
Wind the Ultra Wire forward over the biot body in evenly spaced segments going in the opposite direction of the biot wraps. This counter-wrap locks the biot down and adds durability, so the fly holds up through fish after fish. Tie off the wire and break or clip it cleanly.
Step 7 — Tie In the Wing Case
Select a section of Hareline Cinnamon Tip Turkey Tail Feather, cut to width, and tie it in flat on top of the hook shank just ahead of the abdomen, with the tip pointing back over the tail. Leave it unfolded for now — you'll pull it forward over the thorax to form the wing case in a later step.
Step 8 — Dub the Thorax
Apply a small amount of Wapsi Dark Hare's Mask dubbing to your thread with a tight twist, then build up a full, slightly tapered thorax between the wing case tie-in point and the bead. Hare's mask dubbing has a natural spikiness that traps air bubbles and gives the thorax a buggy, lifelike texture. Don't overdub — you want room to still fold the wing case forward and tie in the CDC collar.
Step 9 — Pull Over the Wing Case
Pull the turkey tail section forward over the top of the dubbed thorax and tie it down tightly just behind the bead. Trim the excess. The dark, mottled wing case is one of the most recognizable features of a mature nymph and really sells the imitation.
Step 10 — Tie In the CDC Collar
Select 2–3 CDC feathers and tie them in just behind the bead so the fibers sweep back along the sides and underneath the fly. Keep it sparse — a few fibers pulse with far more movement than a thick clump. The CDC collar mimics emerging legs and wing pads and gives the fly life even in slow currents.
Step 11 — Finish the Head & Apply UV Resin
Build a small, neat thread head behind the bead and whip finish. Apply a thin coat of Solarez Bone Dry Plus UV Resin over the thread head and into the groove of the bead, then cure it with your UV light. This locks the bead permanently in place and gives the head a clean, professional finish that will outlast multiple fish.
Tips Before You Sit Down at the Vise
Match your bead size to your hook size. For a size 14 XC400, a 3.0mm bead is a great starting point. Size up or down based on how quickly you want the fly to sink.
The biot wrap direction matters. Wrapping rib-side forward creates a smoother body; wrapping the opposite way gives you a more pronounced segmentation. Try both and see what you prefer.
Don't skip the UV resin on the bead. Locking the bead with Solarez keeps it from spinning during the tie and gives you a clean, finished head that holds up to toothy fish and rocky bottoms.
Keep the CDC sparse. A few CDC fibers go a long way. Too much and you lose the movement that makes this collar so effective.
Shop the Full Materials List
Ready to stock your tying bench? Everything you need to tie the Tungsten Jig Assassin is available in our dedicated materials collection — all in one place, ready to ship.
Tight lines, and we'll see you at the vise.
Dakota Angler & Outfitter | Rapid City's Home for Fly Fishing Gear, Guides, and Community