Black Gnat Fly Fishing

Complete Guide to Fly Fishing with the Black Gnat (a perfect Dry midge)

When you talk about Gnat patterns, many aren’t sure what you may be referring to, while others will immediately say the Griffiths Gnat. George Griffith’s Gnat is a very popular pattern and really deserves a place in your fly box.

The issue I have with the pattern and many natural-looking dry flies of this size, is its visibility. I battle to see the fly land and drift through the run. If I don’t see the fly land, I never feel confident with the drift, as I’m always looking to find the fly.

This is where the Hi Vis Black Gnat is so effective. With the addition of a ‘HI VIS’ post tied into the pattern the visual issues are sorted. These are great patterns to fish when the light is bad and the fishing ia a little tough.

In the below article, we will run through the HI VIS Gnat, how to fish it, and how to tie it.

Windy Day Brook Trout
Windy Day Brook Trout – look close caught with a Hi-Vis Black Gnat. Learn how to catch Brook Trout Here 👈

Why the Hi-Vis Black Gnat is Great

This great little pattern has two key factors that make most fall in love with it even before fishing it. Once fished, the relationship is cemented, and so the journey begins.

The Gnat is a very effective pattern to fish, closely related to the Griffiths Gnat. You will know from this that the fly works! Midge patterns are so effective because the midge is the most prominent source of food for trout and many other species year-round.

Secondly, as mentioned earlier, the problem with most midge patterns and many other smaller dry flies is that you just can’t see them. With the addition of a high HI VIS post, the pattern becomes visible even from a mile away, and this makes for great fishing.

Hi-Vis Black Gnat
Hi-Vis Black Gnat 👈 link to YouTube Video

It will cover that section of flies that we use when the going gets tough, or in my case, when the fish are consistently rising on a seam. I know it’s the black midge that they are rising for. That is when I change over to one of these patterns.

This is what I love about this pattern, I have seen many a dry fly thrown at trout without even a sniff of interest, and as soon as you tie on a Gnat and drift it over them, they turn and move to it immediately! It is truly wonderful to watch.

GUIDE PRO TIP – Keeping tiny flies like the black gnat floating can be tough. Read about some techniques in 👉 7 Ways to Keep Your Dry Flies Floating

A Little History on the Hi-Vis Black Gnat   

Looking at this pattern, we can clearly assume that the original pattern would have been the Griffiths Gnat, tied by George Griffith, Trout Fisher and Co-founder of Trout Unlimited.

The pattern was originally thought out to imitate a midge cluster or hatch but has since been thought to resemble a few other insects found floating downstream as well. Whatever it is meant to be, the pattern works very well.

This is what I love about fly fishing and fly tying. The evolution of patterns and techniques where the original style and methods still stay so relevant. This is amazing, I mean, whether you fish a hybrid or an original pattern, they all still catch fish.

The HI VIS Gnat is no exception here and is a great hybrid of the Griffiths Gnat.

What Fish Will a Black Gnat Catch?

The Gnat pattern will catch most species of fish that are found in its water system. Originally tied as a trout pattern but has become very popular with Brown and Brook Trout species. The midge is a very prominent insect in most water systems and thus a very popular food source to imitate.

Learn how to use tiny flies to catch monster brown trout in this guide 👉 How to Fly Fish for Brown Trout

How to Setup a Hi-Vis Black Gnat   

The Hi-Vis Gnat is a dry fly, and as such, a dry fly setup is recommended for use. It is important to fish with what you are comfortable to fish with and know the feeling of. The gnat patterns are usually in size #16 or #18, so a light tippet is used, and you should be comfortable with your setup to hold the tippet’s strength.

I recommend a 9’ or 10’ rod with a leader that you are comfortable with fishing. The leader shouldn’t be shorter than 10,’ and I would fish a tippet in the 6X range. Again, the tippet is dependent on how you fish. It’s pointless fishing a tippet that you keep popping on fish.

Dry Fly Setup
Dry Fly Setup

What Does the Black Gnat Represent

This Hi Vis gnat pattern was originally tied to imitate a cluster of midges or a larger midge. It can, however, be mistaken for other insects. What I like about the Hi Vis Gnat, when tied with a halo hackle around the post, is that the wing case so opens it up to many other species of imitation.

Hi-Vis Black Gnat Favorite Size and Color

Here is a selection of my top three patterns.

  • High Vis Griffiths Gnat– this is what I have been talking about. Umpqua tie is a great version. The sighter posts can be seen from far, and the pattern itself floats really well. I fish this pattern size #16.
  • Cluster– Slightly bigger pattern but equally as effective. Good visibility and is tied on a heavy hook which can have a lot of pressure applied to it. Fished in size #16
  • Erics Midge– is a hybrid of the Hi Vis Black gnat/ Griffiths Gnat. It is this pattern that imitates a few other insects and is a very effective pattern to fish when the fish are being picky. I have this pattern in sizes #16 and #18.

Where to Buy

I’m a firm advocate for tying your own flies. The joy you get from catching a fish on your own patterns is inspiring. But don’t worry fly shops and online stores carry this wonderful patterns.

So, if you don’t tie your own flies, then please buy them from your local fly shop and support them where you can.

If you don’t have a local shop in your town, then I would recommend the Umpqua online store. They have signature tiers and a massive selection of great patterns.

How to Tie Hi Vis Black Gnat


  • Hook: Size 18 Dry Fly Hook
  • Thread: 8/0 Black
  • Body: Peacock Herl
  • Wing: White Para Post
  • Hackle: Grizzly Hen Dry Fly Saddle

Get a FREE PDF Download with the recipe, materials and pictures. Click 👉 Hi-Vis Black Gnat Download

Hi-Vis Black Gnat Tying Steps

  1. Secure hook it the vise.
  2. Wrap a thread base, ending at the bend of the hook.
  3. Tie in the peacock herl and wrap forwards, ending just behind the middle of the shank.
  4. Tie in the Sighter, trimming it off just past the length of the hook shank.
  5. Tie in two hackles, the concave side away from you. The hackle fiber length needs to be roughly the hook gape size. This is a good measure.
  6. Tie in and wrap a peacock strand forward, finishing behind the hook eye.
  7. Wrap the hackle forward and tie off behind the eye.
  8. Head cement the thread, and you are ready to fish.

GUIDE PRO TIP – The Hi Vis Gnat is a great pattern to fish in tandem with a second pattern. (Dry/Dropper Technique) A small midge nymph or sunken midge works wonders behind the first fly. The second fly rides in the water film and with a little weight, just below it. The fish often eat this trailing fly first.

One Last Cast with the Black Gnat   

So, there you have it. Whether you are a dry fly purist who only fishes the original patterns or a bit like me and liked to mix it up a little, then the HI Vis Gnat is a great pattern to have in your box. Learn about other midge patterns I love in this article. Favorite Midge Fly Patterns That Catch Fish

If you are skeptical at first, that’s fine, and so was I, but once you have that first fish on the Gnat and you saw the very decisive eat, then you will be converted, trust me. You will probably stop at your local fly shop on the way home and grab a few.

Whatever you decide to do, make sure you have them to fish when you need them.

Happy Fishing.

Tight Lines!

Looking to Learn the Tips and Techniques for the Fish You Love to Chase? I’ve Got You Hooked Up Below

Kyle Knight writer Guide Recommended

Kyle Knight

Fly fishing has been my passion and pursuit for the past 20 years. I am a South African based fly fisherman who loves nothing more than spending a day on the water. Fly fishing is more than catching fish, being in the outdoors with good friends and family is what it is all about.

Scroll to Top