Stoneflies
Caddisflies
Damselflies & dragonflies
Gammarids
- Ecology: Good
- Chemical: Unknown
WFD classification · SI62VT13
Rules at a glance
- Permit required
- Barbless
Water temperature for Grayling
Ideal9.3°Cideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn through November is prime — September into November the grayling get serious. Cold water, midday warmth, and the duns and spinners that come off the limestone runs.
Where
Faster water at the heads of pools and through the riffles — gravel runs where grayling shoal up. Deeper glide tails into autumn as the water cools.
Method
Euro-nymphing primary — Perdigons and dropper-rigged spider patterns through the pocket water. Switch to dries when sedges or olives come off. Slovenian grayling are particular about presentation.
Kit
10 ft #3 nymphing rod is the default; 9 ft #4 if you'd rather dry-fish. 4 to 5 lb fluoro tippet, 12 ft leader.
Why this works
Excellent — water temperature is working for you, but time of day is the limiting factor today. Grayling is active in the cooler margins of the season.
Likely species
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Net-spinning caddisAlso possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
- CapererAlso possibleLower confidence#10–12 · AdultBig autumn sedge; fish dry at last light.
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 9 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 4 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
1
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
sizes_14_18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- Fishing licence + permit from ribiške družine
- No live bait.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
- Kanomljica6.0 kmMarble trout · Marble brown hybrid trout · Brown trout77
- River Trebuščica13 kmBrown trout · Marble trout
- Hubelj13 kmMarble trout · Marble brown hybrid trout · Brown trout
- Cerknica (Idrijca tributary)13 kmMarble trout · Marble brown hybrid trout · Brown trout
- Vipava17 kmMarble trout · Marble brown hybrid trout · Brown trout
Gallery · 6
Idrijca near Most na Soči 
Idrijca in the Strug gorge 
Idrijca upstream from Idrijska Bela 
Idrijca in the Strug gorge 
Idrijca at Spodnja Idrija Terrain map
Water quality (WFD)
The full read · show the working · for Grayling · confidence 55%
How the 80 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time15 × 13%2.0
Pressure80 × 7%5.6
Insect activity51 × 12%6.1
Conditions total= 75
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 1 March → 30 September
- Grayling 16 May → 30 November
Slovenian common default: grayling 16 May – 30 November (lipan). Slovenia is permit and fishing district controlled — dates may vary by specific water. Always check the Ribiška Družina (fishing district) permit for the specific beat. The Soča, Idrijca, and Sava system hold world-class grayling alongside marble trout.
Prime sport 1 September → 30 November
- Marble trout 1 April → 31 October
Related guides
Booking & contacts
Permits & access
Clubs & associations
- RD IdrijaPermit required · Above Stopnik
- RD TolminPermit required · Stopnik to the Soča confluence
Idrijca
Water temperature for Grayling
Ideal9.3°Cideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn through November is prime — September into November the grayling get serious. Cold water, midday warmth, and the duns and spinners that come off the limestone runs.
Where
Faster water at the heads of pools and through the riffles — gravel runs where grayling shoal up. Deeper glide tails into autumn as the water cools.
Method
Euro-nymphing primary — Perdigons and dropper-rigged spider patterns through the pocket water. Switch to dries when sedges or olives come off. Slovenian grayling are particular about presentation.
Kit
10 ft #3 nymphing rod is the default; 9 ft #4 if you'd rather dry-fish. 4 to 5 lb fluoro tippet, 12 ft leader.
Why this works
Excellent — water temperature is working for you, but time of day is the limiting factor today. Grayling is active in the cooler margins of the season.
Likely species
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Net-spinning caddisAlso possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
- CapererAlso possibleLower confidence#10–12 · AdultBig autumn sedge; fish dry at last light.
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 9 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 4 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Supporters see what else is on the menu.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
1
Evening SedgeHatch
2
3
3
3
2
Alpine RhithrogenaHatch
1
2
2
1
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
sizes_14_18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- Fishing licence + permit from ribiške družine
- No live bait.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 6
Idrijca near Most na Soči Idrijca in the Strug gorge Idrijca upstream from Idrijska Bela Idrijca in the Strug gorge Idrijca at Spodnja Idrija Terrain map
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · SI62VT13
The full read · show the working · for Grayling · confidence 55%
How the 80 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time15 × 13%2.0
Pressure80 × 7%5.6
Insect activity51 × 12%6.1
Conditions total= 75
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 1 March → 30 September
- Grayling 16 May → 30 November
Slovenian common default: grayling 16 May – 30 November (lipan). Slovenia is permit and fishing district controlled — dates may vary by specific water. Always check the Ribiška Družina (fishing district) permit for the specific beat. The Soča, Idrijca, and Sava system hold world-class grayling alongside marble trout.
Prime sport 1 September → 30 November
- Marble trout 1 April → 31 October
Related guides
Booking & contacts
Permits & access
Clubs & associations
- RD IdrijaPermit required · Above Stopnik
- RD TolminPermit required · Stopnik to the Soča confluence