Freestone · Limestone · Friuli Venezia Giulia / Valli del Natisone

Natisone

Natisone venue image

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.

Poor · Marble Trout
Blue-Winged Olive · 18-20
Poorlive now
Not the day for it
Low and clear — careful approach country. A morning for the obvious fish only.
90% confidence
What moved it
  • LevelDry recentlyNo gauge reading
  • Water temp22.8°C
  • ClarityClear
Today's fly
Blue-Winged Olive
Blue-Winged Olive18-20
Upstream dry, on top
Conditions on the water
Estimate
Level
Dry recently
No gauge reading
Water temp22.8°C
ClarityClear
Weather31°C
WindSW 8 km/h
Pressure1022 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Water temperature for Marble Trout
Warm — slow
23°C est.ideal 8–13°C
0°14°28°
How to fish it · for Marble Trout
When
Dawn and dusk are best. The RPS water around Cividale del Friuli (Ponte del Diavolo to Ponte di Loch Linder/Vernasso) has long been regarded as some of the region's best marble trout fishing, historically holding well over a hundred spawning nests in a good year. Season 29 March to 27 September; single barbless hook, one fish a day.
Where
Deep pools and undercut limestone banks through the No-Kill and RPS reaches around Cividale, and in the gorge sections downstream of Vernasso.
Method
Streamer on intermediate or sink-tip, fished slow through the deep pools; in low, clear water a size down and a longer pause pays off.
Kit
9 to 10 ft #6/7, intermediate line, 8 to 10 lb fluoro, baitfish streamers. Wet net, handle with care — the No-Kill water asks for it.
Why this works
Water at 22.8°C. This is the line where catch-and-release kills marble trout. Do not fish for them today.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 2 active hatches hour by hour 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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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
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
Marble 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.

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
Cooler water nearby · 1
Probably above the Marble Trout safety line — these are likely cooler, but carry a thermometer.
River Bača
19 km
15.7°C
Brown trout · Marble trout · Rainbow trout
Gallery · 1
  1. Terrain map of the venue
    Terrain map
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 Marble Trout · confidence 90%
How the 10 is built — score × weight = contribution
Temperature6 × 28%1.7
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time65 × 13%8.5
Pressure80 × 7%5.6
Insect activity58 × 12%7.0
Limiting factor: Water temperature (22.8°C) is outside Marble Trout's preferred range (8–13°C)= 53
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 8–13 °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