When to use it
- Where Isonychia populations are established.
- During the local late-afternoon or evening seasonal window.
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Reviewed representative comparison← Fly Box
Pattern family · guide 52
Isonychia and Mahogany Dun Patterns
A stage-based Isonychia family, including report wording such as Mahogany Dun or Slate Drake.
- Size range
- Often #10–14; verify locally
- Colors reviewed
- claret, mahogany, brown-black, dun wing
- Imitates
- Isonychia nymph, Isonychia emerger, Mahogany Dun or Slate Drake adult, Isonychia spinner
Isonychia nymphs are active swimmers; emergers, parachute or other dry forms, and spinners occupy different levels. Mahogany Dun can be regional hatch wording, so it does not identify one exact fly recipe.
Technical illustration
Representative forms
Isonychia and Mahogany Dun Patterns stage map
A family-level comparison of Swimming Isonychia nymph, Isonychia emerger, Mahogany Dun or spinner; no single drawing represents the whole family.
- View
- stage comparison map
- Color shown
- claret, mahogany, brown-black, and dun
- Look for
- swimming nymph; trailing-shuck emerger; Mahogany Dun adult; spinner
On the water
Narrow the family.
The river, depth, insects, and fish behavior still decide the final presentation. These are reviewed starting points—not a claim about what is happening today.
How to fish it
- Give swimming nymphs controlled movement; use emergers and dries as the insects reach the surface.
Mistakes to avoid
- Dead-drifting every Isonychia nymph by default.
- Treating Mahogany Dun as one universal exact fly.
Variant control
Small changes matter.
This stage comparison keeps materially different forms labeled. It is a family guide, not a claim that one fly represents every stage or local species.
Representative stage forms
Isonychia nymphs are active swimmers; emergers, parachute or other dry forms, and spinners occupy different levels. Mahogany Dun can be regional hatch wording, so it does not identify one exact fly recipe.- Colors shown
- claret, mahogany, brown-black, dun wing
- Weighting
- Weight and buoyancy depend on the life stage and exact named pattern.
Review trail
Sources, rights, and limits.
Pattern facts were reviewed on 2026-07-12. Every image has its own rights record; photographed hand-tied flies may still vary slightly in proportion.