Freestone · Limestone · Haute-Savoie

Fier

Fier venue image
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The Fier cuts through the Bornes and Aravis on its way down towards the Rhône — fast, cold, limestone-clear, and punctuated with gorges that turn casual fishing into a day's expedition.

Marginal · Brown Trout
Small Perdigón · 16-20
Marginallive now
Slow going — pick your moments
River steady at a fishable height. Take your time — read the water before you cast.
80% confidence
What moved it
  • LevelProxyvia Borne
  • Water temp18.8°C
  • ClarityClear
Today’s fly
Small Perdigón
Small Perdigón16-20
Euro-nymph
Conditions on the water
Proxy gauge
Level
Steady
Proxy
via Borne
Water temp18.8°C
ClarityClear
Weather20°C
WindE 5 km/h
Pressure1020 hPa
Rain · recent13.6 mm
Rain · ahead7.9 mm

No gauge on this water — conditions are inferred from Borne. The trend transfers, the absolute level does not.

Water temperature for brown trout
Warm — slow
19°C est.ideal 1016°C
0°14°28°
How to fish it · for brown trout
When
Through the open trout season. Spring once snowmelt drops; sedges through summer evenings; small dark flies into autumn close.
Where
Pool tails and pocket water through the Haute-Savoie valley. Alpine freestone character — clear water, fast pockets.
Method
Upstream dry to risers; dry-dropper through the riffles. The water reads clear — long leader, fine tippet. Move slowly, cast accurately.
Kit
9 ft #4 — French freestone default. Floating line, 12 ft leader to 4 to 5 lb fluoro. Studded boots.
Why this works
⚠️ Water at 18.8°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots. Otherwise poor — water clarity is in the right range.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 7 active hatches hour by hour with Pro.

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Evidence
Survey-backed · regionalModerate confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · July highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Alpine RhithrogenaHatch
2
3
3
2
Sculpin / Baitfish (Rivers)Hatch
2
3
3
3
3
3
3
3
2
March BrownHatch
2
3
2
Large StoneflyHatch
2
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Brown Trout fly box
What's coming
Plan ahead
5-day outlook
Cooler water nearby · 1
Water here around 19°C — probably warm enough to stress brown trout. These are likely cooler.
Gallery · 1
  1. Terrain map of the venue
    Terrain map
About this water

The Fier cuts through the Bornes and Aravis on its way down towards the Rhône — fast, cold, limestone-clear, and punctuated with gorges that turn casual fishing into a day's expedition. The upper and middle reaches hold wild brown trout in pocket water that rewards the kind of fishing where you can read the seams in your sleep. Standard Alpine drill: heavy nymph, tight line, pick the cushion behind each boulder. Dry fly comes into its own when the olives and caddis are working in the slower pools between the ragged sections. The gorges limit access to specific entry points — the AAPPMA marks them — and once you're in, you may not get out easily, so plan accordingly. The prime window is May through late June. By July the lower reaches warm and the fishing moves upstream.

  • Limestone
Water quality (WFD)
  • EcologyModerate
  • ChemicalUnknown

WFD classification · FRDR530

The full read · show the working · for brown trout · confidence 80%
How the 35 is built — score × weight = contribution
Temperature42 × 28%11.8
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time45 × 13%5.9
Pressure80 × 7%5.6
Insect activity65 × 12%7.8
Conditions total= 66
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Borneproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
  • Trout2nd Saturday of March → 3rd Sunday of September
Related guides
Booking & contacts