10 Common Fly Fishing Fly Mistakes: What Fly to Use and When (And How to Fix Them)

By Mike Tenner | TroutFlies Australia

When it comes to fly fishing, even seasoned anglers make simple fly selection mistakes that can cost them fish. Knowing what fly to use, when to use it, and how to fix common errors can turn a frustrating outing into a day full of hookups.

Here are the 10 most common fly fishing fly mistakes—and how to correct them.

1. Choosing the Wrong Fly for the Hatch

Mistake: Fishing a fly that doesn’t match the insects currently on the water.
Fix: Take a few minutes to observe the hatch. Match the size, colour, and behaviour of the bugs with flies like the Highland Dun – Claret Brown or Mike’s Beetle. Matching the hatch is crucial, especially in pressured waters.

2. Using Flies That Are Too Big (or Too Small)

Mistake: Using a fly that’s the wrong size for the water conditions or target species.
Fix: In clear, calm water, downsize your flies. In rough or dirty water, go larger. Try a size 16 Pheasant Tail Nymph for spooky trout or a size 10 Woolly Bugger when visibility is low.

3. Sticking to Just One Pattern

Mistake: Relying on your “lucky fly” even when it’s not working.
Fix: Adapt. Conditions change and fish get selective. Build a fly box with variety—nymphs, dries, wets, and streamers. Include Easy Peasy Ant, Parachute Adams, and Clouser Minnows for versatility.

4. Ignoring Seasonal Fluctuations

Mistake: Using summer flies in winter or vice versa.
Fix: Adjust your selection based on the season. In winter, fish deeper with weighted nymphs or egg patterns. In warmer months, go for surface terrestrials like beetles and ants.

5. Not Adjusting for Water Type

Mistake: Fishing river flies in stillwater—or vice versa.
Fix: Lakes often require different tactics. Use Damsel Nymphs, Booby Flies, or Suspender Buzzers in stillwater. In rivers, rely on Copper Johns, Elk Hair Caddis, and Hare’s Ear Nymphs.

6. Overlooking Terrestrials

Mistake: Forgetting about ants, beetles, and hoppers during peak season.
Fix: Late spring to early autumn is terrestrial time. Always carry patterns like Mike’s Beetle, Easy Peasy Ant, and foam hoppers in your summer fly box.

7. Fishing Worn-Out Flies

Mistake: Using flies that are chewed, damaged, or missing parts.
Fix: Check your flies regularly. Frayed hackle or bent hooks mean lower success. Replace them with fresh patterns—especially ones you know produce.

8. Using Flashy Flies in Clear Water

Mistake: Spooking fish with too much flash.
Fix: In crystal-clear water, tone it down. Go natural with flies like the CDC Caddis, PTN, or March Brown. Save the flashy patterns for murky or turbulent conditions.

9. Fishing Surface Flies in Fast Currents

Mistake: Watching your dry fly get drowned in rapid water.
Fix: Switch to more buoyant patterns like the Stimulator or Klinkhåmer. Better yet, try a dry-dropper rig to cover both surface and subsurface zones.

10. Not Replacing Lost Confidence Patterns

Mistake: Losing your go-to fly and not having backups.
Fix: Always carry duplicates of your top performers like the Beadhead Hare’s Ear, Woolly Bugger, and Mike’s Beetle. Confidence flies are crucial—don’t run out when they’re working.

Final Thoughts: Mastering Fly Selection

Fly selection can make or break your day. By avoiding these 10 common mistakes—and packing your fly box with the right patterns—you’ll drastically improve your success on the water.

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👉 www.troutflies.com.au