Rules at a glance
- Permit required
Water temperature for Grayling
Ideal9°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Midday window — grayling feed best from late morning into early afternoon.
Where
Work runs and glides — grayling shoal in the bottom third of the water column.
Method
Tight-line nymph the bottom third with weighted patterns.
Kit
10 ft #3 rod, floating line, long leader to 4 lb fluoro for nymphs.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour. Grayling feeds actively in cold water — peak winter sport.
Likely species
Mayflies
Mayflies- Turkey BrownMost likelyLower confidence#14–16 · DunSmall spring dun on slower glides and margins.
- Late March BrownAlso possibleLower confidence#12–14 · DunLate-season upland riffle dun, dusk emergence.
- Iron BlueAlso possibleNearest relative#16–18 · DunCold, grey day — the dun sits long. Good dry-fly water.
- Blue-winged oliveAlso possible#16–18 · DunDuns are up; a sherry spinner fall may follow.
Stoneflies
Caddisflies
Caddisflies- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- GrannomAlso possibleNearest relative#14–16 · PupaPupa first, then dries as the adults come off.
- Saddle-case CaddisAlso possibleLower confidenceNearest relative#16–18 · AdultTiny blackish caddis; fast riffles, early summer.
Gammarids
Molluscs
- Pond snailsMost likelyLower confidence#10–12–14 · AdultDead-drift or twitch a snail pattern near weed beds.
Hatch timeline · todayPeak at 13:00
12:00(now) — Iron Blue
Stage: On emergersApproach: Emerger or dryActivity: 86%
Also:Black Midge75%Autumn Needle Fly45%
Weather boostDegree-days at peak5 food groups active
Peak activity at 13:00 — Iron Blue (Iron Blue, Weather boost)
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 2 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 · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Grayling seasonSeason
1
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
Permits & access
Permit required — see local rules.
- Zavod za ribištvo Slovenije (ZZRS) district, NOT RD Tolmin — a separate permit
- Fly only, artificial fly
- Day and 3-day permits in catch-and-release and catch-and-take tiers, with or without the Lepena and Koritnica tributaries
- Barbless is the norm on marble water and is required on the neighbouring RD Tolmin district — confirm the current ZZRS terms when you buy rather than assuming they match.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
The full read · show the working · for Grayling · confidence 90%
How the 91 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity65 × 12%7.8
Conditions total= 83
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Rainbow trout 1 April → 31 October
- Grayling 16 May → 31 October
Adriatic grayling (lipan). ZZRS sells permits for this district only between 1 April and 31 October, so the national grayling window closes early here in practice. Check the current permit terms.
Prime sport 1 September → 31 October
- Marble trout 1 April → 30 September
Related guides
Booking & contacts
Upper Soča (Trenta)
Water temperature for Grayling
Ideal9°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Midday window — grayling feed best from late morning into early afternoon.
Where
Work runs and glides — grayling shoal in the bottom third of the water column.
Method
Tight-line nymph the bottom third with weighted patterns.
Kit
10 ft #3 rod, floating line, long leader to 4 lb fluoro for nymphs.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour. Grayling feeds actively in cold water — peak winter sport.
Likely species
Mayflies
- Turkey BrownMost likelyLower confidence#14–16 · DunSmall spring dun on slower glides and margins.
- Late March BrownAlso possibleLower confidence#12–14 · DunLate-season upland riffle dun, dusk emergence.
- Iron BlueAlso possibleNearest relative#16–18 · DunCold, grey day — the dun sits long. Good dry-fly water.
- Blue-winged oliveAlso possible#16–18 · DunDuns are up; a sherry spinner fall may follow.
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- GrannomAlso possibleNearest relative#14–16 · PupaPupa first, then dries as the adults come off.
- Saddle-case CaddisAlso possibleLower confidenceNearest relative#16–18 · AdultTiny blackish caddis; fast riffles, early summer.
Molluscs
- Pond snailsMost likelyLower confidence#10–12–14 · AdultDead-drift or twitch a snail pattern near weed beds.
Hatch timeline · todayPeak at 13:00
12:00(now) — Iron Blue
Stage: On emergersApproach: Emerger or dryActivity: 86%
Also:Black Midge75%Autumn Needle Fly45%
Weather boostDegree-days at peak5 food groups active
Peak activity at 13:00 — Iron Blue (Iron Blue, Weather boost)
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 2 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 · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Grayling seasonSeason
1
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
Permits & access
Permit required — see local rules.
- Zavod za ribištvo Slovenije (ZZRS) district, NOT RD Tolmin — a separate permit
- Fly only, artificial fly
- Day and 3-day permits in catch-and-release and catch-and-take tiers, with or without the Lepena and Koritnica tributaries
- Barbless is the norm on marble water and is required on the neighbouring RD Tolmin district — confirm the current ZZRS terms when you buy rather than assuming they match.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
The full read · show the working · for Grayling · confidence 90%
How the 91 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time70 × 13%9.1
Pressure80 × 7%5.6
Insect activity65 × 12%7.8
Conditions total= 83
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Rainbow trout 1 April → 31 October
- Grayling 16 May → 31 October
Adriatic grayling (lipan). ZZRS sells permits for this district only between 1 April and 31 October, so the national grayling window closes early here in practice. Check the current permit terms.
Prime sport 1 September → 31 October
- Marble trout 1 April → 30 September
Related guides
Booking & contacts