Catgut Biothread

(5 customer reviews)

US$3.51

  • One of the best materials for tying killer, super-realistic nymphs.
  • Unique and versatile – a top choice material among the world’s most experienced fly tyers.
  • It is opaque, solid-colored when dry, and becomes milky translucent and shiny when wet.
  • When submerged in water, it becomes very soft, flexible, and stretchable, which makes it super easy to work with.
  • As it soaks in water, its volume also increases, giving a plump appearance to the fly.
  • The most amazing benefit of using this material is the way it looks in water – flies tied with it look extremely authentic, have lifelike texture, and super-high shine.
  • The material has been treated to extend its durability under water.
  • To apply, soak the part you want to use in warm water for 3-5 minutes prior to tying. The color will change from opaque to more milky and transparent and the material will be super-flexible and easy to wrap.
  • When the fly dries, the body will go back to its solid-colored state.
  • By using various colored threads underneath it for the underbody, different effects can be achieved as the color peaks through the wet material.
  • About 50 cm long (about 20”), comes in four diameters and a wide range of colors.
  • Sizes (Diameters) and hook recommendations:
    • Extra Small (0.18mm) – for hooks #16 and #20
    • Small (0.3mm) – for hooks #14 and #16
    • Medium (0.5mm) – for hooks #12 and #14
    • Large (0.7mm) – for hooks #8 and #10
  • Absolutely perfect for making bodies for nymphs and emerger flies.
  • Also a great choice material for making loops on traditional salmon flies (small diameters, in particular, XS and S)
  • See the Description section below for more details, tying instructions, and more!

ThumbnailSKUColorSizeWishlistPriceQuantity 
Catgut Biothread - Natural
107-0114XS-01NaturalExtra Small US$3.51
Catgut Biothread - Natural
107-0114SM-01NaturalSmall US$3.51
Catgut Biothread - Natural
107-0114ME-01NaturalMedium US$3.51
Catgut Biothread - Natural
107-0114LG-01NaturalLarge US$3.51
Catgut Biothread - Brown
107-0114XS-02BrownExtra Small US$3.51
Catgut Biothread - Brown
107-0114SM-02BrownSmall US$3.51
Catgut Biothread - Brown
107-0114ME-02BrownMedium US$3.51
Catgut Biothread - Brown
107-0114LG-02BrownLarge US$3.51
Catgut Biothread - Cocoa Brown
107-0114XS-03Brown CocoaExtra Small US$3.51
Catgut Biothread - Cocoa Brown
107-0114SM-03Brown CocoaSmall US$3.51
Catgut Biothread - Cocoa Brown
107-0114ME-03Brown CocoaMedium US$3.51
Catgut Biothread - Cocoa Brown
107-0114LG-03Brown CocoaLarge US$3.51
Catgut Biothread - Caddis Green
107-0114XS-04Caddis GreenExtra Small US$3.51
Catgut Biothread - Caddis Green
107-0114SM-04Caddis GreenSmall US$3.51
Catgut Biothread - Caddis Green
107-0114ME-04Caddis GreenMedium US$3.51
Catgut Biothread - Caddis Green
107-0114LG-04Caddis GreenLarge US$3.51
Catgut Biothread - Cinnamon
107-0114XS-05CinnamonExtra Small US$3.51
Catgut Biothread - Cinnamon
107-0114SM-05CinnamonSmall US$3.51
Catgut Biothread - Cinnamon
107-0114ME-05CinnamonMedium US$3.51
Catgut Biothread - Cinnamon
107-0114LG-05CinnamonLarge US$3.51
Catgut Biothread - Fluo Pink
107-0114XS-06Fluo PinkExtra Small US$3.51
Catgut Biothread - Fluo Pink
107-0114SM-06Fluo PinkSmall US$3.51
Catgut Biothread - Fluo Pink
107-0114ME-06Fluo PinkMedium US$3.51
Catgut Biothread - Fluo Pink
107-0114LG-06Fluo PinkLarge US$3.51
Catgut Biothread - Fluo Yellow
107-0114XS-07Fluo YellowExtra Small US$3.51
Catgut Biothread - Fluo Yellow
107-0114SM-07Fluo YellowSmall US$3.51
Catgut Biothread - Fluo Yellow
107-0114ME-07Fluo YellowMedium US$3.51
Catgut Biothread - Fluo Yellow
107-0114LG-07Fluo YellowLarge US$3.51
Catgut Biothread - Green Olive
107-0114XS-08Green OliveExtra Small US$3.51
Catgut Biothread - Green Olive
107-0114SM-08Green OliveSmall US$3.51
Catgut Biothread - Green Olive
107-0114ME-08Green OliveMedium US$3.51
Catgut Biothread - Green Olive
107-0114LG-08Green OliveLarge US$3.51
Catgut Biothread - Olive
107-0114XS-09OliveExtra Small US$3.51
Catgut Biothread - Olive
107-0114SM-09OliveSmall US$3.51
Catgut Biothread - Olive
107-0114ME-09OliveMedium US$3.51
Catgut Biothread - Olive
107-0114LG-09OliveLarge US$3.51
Catgut Biothread - Olive Brown
107-0114XS-10Olive BrownExtra Small US$3.51
Catgut Biothread - Olive Brown
107-0114SM-10Olive BrownSmall US$3.51
Catgut Biothread - Olive Brown
107-0114ME-10Olive BrownMedium US$3.51
Catgut Biothread - Olive Brown
107-0114LG-10Olive BrownLarge US$3.51
Catgut Biothread - Orange
107-0114XS-11OrangeExtra Small US$3.51
Catgut Biothread - Orange
107-0114SM-11OrangeSmall US$3.51
Catgut Biothread - Orange
107-0114ME-11OrangeMedium US$3.51
Catgut Biothread - Orange
107-0114LG-11OrangeLarge US$3.51
Catgut Biothread - Red
107-0114XS-12RedExtra Small US$3.51
Catgut Biothread - Red
107-0114SM-12RedSmall US$3.51
Catgut Biothread - Red
107-0114ME-12RedMedium US$3.51
Catgut Biothread - Red
107-0114LG-12RedLarge US$3.51
Catgut Biothread - Yellow
107-0114XS-13YellowExtra Small US$3.51
Catgut Biothread - Yellow
107-0114SM-13YellowSmall US$3.51
Catgut Biothread - Yellow
107-0114ME-13YellowMedium US$3.51
Catgut Biothread - Yellow
107-0114LG-13YellowLarge US$3.51

Catgut Biothread

Catgut Biothread is one of the best materials for tying extra effective, super-realistic nymphs. Its very unique characteristics and versatility make it a top choice among the world’s most experienced fly tyers. This material is opaque, solid-colored when dry, and becomes milky translucent and shiny when wet. When submerged in water, it also becomes very soft, flexible, and stretchable, which makes it super easy to work with. As it soaks in water, its volume also increases, giving a plump appearance to the fly. The most amazing benefit of using this material is the way it looks in water – flies tied with it look extremely authentic, have lifelike texture, and super-high shine. The material has been treated to extend its durability underwater.

To apply, soak the part you want to use in warm water for 3-5 minutes prior to tying. The color will change from opaque to more milky and transparent and the material will be super-flexible and easy to wrap. When the fly dries, the body will go back to its solid-colored state. By using various colored threads underneath it for the underbody, different effects can be achieved as the color peaks through the wet material. The combinations are really limitless. See below for detailed instructions.

Catgut Biothread is about 50 cm long (about 20”), comes in four diameters, and wide range of colors.

Sizes (Diameters) and hook recommendations:

  • Extra Small (0.18mm) – for hooks #16 and #20
  • Small (0.3mm) – for hooks #14 and #16
  • Medium (0.5mm) – for hooks #12 and #14
  • Large (0.7mm) – for hooks #8 and #10

Catgut Biothread is perfect for making bodies for nymphs and emerger flies. It is also a great choice material for making loops on traditional salmon flies (small diameters, in particular, XS and S)

How to use Catgut Biothread

Tying a Classic Micro Nymph with Catgut Biothread

Tying the Micro Nymph with Catgut - Final Fly - Wet

TYING A CLASSIC MICRO NYMPH

with Catgut Biothread

First Step

Prior to tying, soak the part of Catgut Biothread that you want to use in warm water for 3-5 minutes. The color will change from opaque to more milky and transparent and the material will be super-flexible and easy to wrap. When the fly dries, the body will go back to its solid-colored state.

Tying the Micro Nymph with Catgut - Step 1
Tying the Micro Nymph with Catgut - Step 2
Tying the Micro Nymph with Catgut - Step 3
Tying the Micro Nymph with Catgut - Step 4
Tying the Micro Nymph with Catgut - Step 5
Tying the Micro Nymph with Catgut - Step 6
Tying the Micro Nymph with Catgut - Final Fly - Dry

Finished Micro Nymph with dry body

Tying the Micro Nymph with Catgut - Final Fly - Getting Wet

Micro Nymph after a few seconds of soaking in water

Tip

By using various colored threads for underbody, different effects can be achieved as the color peaks through the wet material. The combinations are really limitless.

Tying the Micro Nymph with Catgut - Final Fly - with Green Underbody thread

Micro Nymph with green underbody thread

Tying the Micro Nymph with Catgut - Final Fly - with Green Underbody Thread - When Wet

Micro Nymph with green underbody thread - soaked

Tying the Micro Nymph with Catgut - Final Fly - with Brown Underbody Thread

Micro Nymph with brown underbody thread

Tying the Micro Nymph with Catgut - Final Fly - with Brown Underbody Thread - When Wet

Micro Nymph with brown underbody thread - soaked

Video Tutorial

Fly Tying a Catgut Caddis Pupa

For a full list of ingredients for this recipe, go here. 

Weight 0.005 kg
Dimensions 13 × 7 × 0.3 cm
Manufacturer

Color

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Size

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5 reviews for Catgut Biothread

  1. Jeff

    This is an absolute must have product. A real game changer on the hook once wet. Quick soak in warm water before tying and it applies like dream. Sells out quickly, so get your order in.

  2. Robert Spangler (verified owner)

    Great material for segmented body.

  3. K Rentzheimer (verified owner)

    I’ve been waiting for a few years to tie with cat gut. But every time I went to order it was sold out. Finally purchased in the Olive green and Natural. All I can say is WOW! Simple tie and when wet looks fantastic. Pleasantly surprised. Will be buying more.

  4. Brandon Fobes (verified owner)

    I was originally scared from using this material as it is something I’ve never heard of or used, but after using it I quickly fell in love with it

  5. Rick Xavier (verified owner)

    Cat gut is great material for caddis abdomen bodies. Provides a nice transparency to the body and because the material is a bit thicker creates a nice representation of caddis anatomy.

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