Freestone · Limestone · Friuli Venezia Giulia / Valli del Natisone

Natisone

Natisone terrain map

A limestone-and-marl river that rises barely inside Italy, loops briefly through Slovenia, and re-enters near Stupizza to carve gin-clear gorges down through the Valli del Natisone to Cividale del Friuli.

Marginal · Brown Trout
Elk Hair Caddis · 12-16
Marginallive now
Slow going — pick your moments
River temperature is the limiting factor today, not the flow. Fish dawn or dusk if you go at all, and handle everything with extra care.
80% confidence
What moved it
  • Level0.18 m
  • Water temp20.0°C
  • ClarityClear
Today's fly
Elk Hair Caddis
Elk Hair Caddis12-16
Upstream dry, on top
Conditions on the water
Live gauge
Level
Steady
0.18 m
Water temp20.0°C
ClarityClear
Weather23°C
WindNE 14 km/h
Pressure1018 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

Water temperature for Brown Trout
Warm — slow
20°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Through the FVG trout season. The Natisone runs gin-clear for a limestone river, so approach and light matter more here than almost anywhere else in the region.
Where
Pool tails and current seams through the gorges below Pulfero and San Pietro al Natisone, where the valley narrows.
Method
Long, fine leaders and careful wading — the clarity that makes this river beautiful also makes it easy to put fish down. Upstream nymph and dry-dropper both work if you stay unseen.
Kit
9 to 10 ft #4, floating line, 12 ft leader to 4 to 5 lb fluoro, fined down further in low water.
Why this works
Water at 20°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Likely species
Mayflies
  • Blue-winged oliveMost likely
    #16–18 · Dun
    Duns are up; a sherry spinner fall may follow.
  • Iron BlueAlso possible
    #16–18 · Dun
    Cold, grey day — the dun sits long. Good dry-fly water.
  • Large dark oliveAlso possible
    #14–16 · Emerger
    Dead-drift the emerger — it's sitting in the film.
  • Anglers curse mayfliesAlso possibleLower confidence
    #20–22 · Spinner
    Go tiny: 20-22 spent spinner, single fly, long tippet.
Caddisflies
  • Net-spinning caddis (S. Europe)Most likelyLower confidence
    #12–14–16 · Pupa
    Widespread riffle net-spinner; evening emergence.
  • Satin sedgeAlso possibleLower confidence
    #12–14 · Egg-laying
    Skitter it at dusk — this one's fished, not dead-drifted.
  • GrannomAlso possible
    #14–16 · Pupa
    Pupa first, then dries as the adults come off.
Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 6 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 3 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 with Pro.

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Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
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

A fuller Italian trout and grayling box for the southern Alps and northern limestone/alpine systems. It keeps the marble-trout streamer accent, but adds proper grayling dries and bugs, competition nymphs, caddis/olive work, terrestrials, pocket-water dries and alpine lake patterns.

FC
Foam Caddis / Sedge Hog
12-16 · Pattern
Upstream dry, on top
Permits & access
Permit required — see local rules.
  • ETPI regional licence required
  • FVG Zone B season: trout open 07:00 on 29 March to 27 September, catch-and-release extension to 31 October
  • Marble trout minimum size follows the FVG regional default of 50cm in this collegio (Collegio 13 Cividale) — no local 35cm exception found for the Natisone
  • Grayling minimum size 60cm, one retained specimen per angler per calendar year region-wide
  • Single barbless hook mandatory on the Cividale No-Kill and RPS water.
What's coming
Plan ahead
5-day outlook
Water here around 20°C. Nothing cooler within range — carry a thermometer.
About this water

A limestone-and-marl river that rises barely inside Italy, loops briefly through Slovenia, and re-enters near Stupizza to carve gin-clear gorges down through the Valli del Natisone to Cividale del Friuli. Marble trout have historically spawned here in real numbers — well over a hundred nests in a good year on one well-studied stretch — alongside brown trout and grayling. The No-Kill and RPS water around Cividale is some of the most respected marble trout fishing in the region, and demands quiet wading and fine tippet in water this clear.

  • Limestone
The full read · show the working · for Brown Trout · confidence 80%
How the 28 is built — score × weight = contribution
Temperature25 × 28%7.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity66 × 12%7.9
Conditions total= 63
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
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
Apple MapsGoogle Maps
Seasons & zones
  • Trout 2026-03-29 → 2026-09-27
  • Grayling 2026-06-01 → 2026-09-27

    Rules are set at province or association level — check locally.

  • Marble trout 2026-03-29 → 2026-09-27
Related guides
Grayling Playbookgrayling tacticsEuro Nymphingsubsurface methods
Booking & contacts