Rules at a glance
- Free fishing
- Fly only
Water temperature for Grayling
Ideal11.8°Cideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
June onward, holding up well into the back end of the season — the Rienza's grayling population is strong enough that it's worth planning a day specifically around them.
Where
Gravel runs and riffle heads through the middle valley, and the faster seams at the head of the longer glides lower down.
Method
Euro-nymph the faster water; switch to dries when the afternoon hatch shows on the flats.
Kit
10 ft #3 nymphing rod, 4-5 lb fluoro; 9 ft #4 for dries. 12 ft leader.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour.
Likely species
Mayflies
Mayflies- Blue-winged oliveMost likely#16–18 · DunDuns are up; a sherry spinner fall may follow.
- Large dark oliveAlso possible#14–16 · EmergerDead-drift the emerger — it's sitting in the film.
- Turkey BrownAlso possibleLower confidence#14–16 · DunSmall spring dun on slower glides and margins.
- Ephemera vulgata (lake mayfly)Also possibleLower confidenceNearest relative#8–10–12 · NymphLarge lake/slow-river mayfly; burrows soft sediment.
Caddisflies
Caddisflies- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Net-spinning caddis (S. Europe)Also possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
- GrannomAlso possibleNearest relative#14–16 · PupaPupa first, then dries as the adults come off.
- Stone-case caddisAlso possibleLower confidenceNearest relative#14–16–18 · NymphTiny stone-cased larva; clean gravel riffles.
Stoneflies
Stoneflies- Little Brown StoneMost likelyLower confidence#16–18 · AdultSmall dark stone nymph or adult in early spring.
- NeedleflyAlso possibleLower confidenceNearest relative#16–18 · AdultSmall slender stonefly; clean, cold headwater riffles.
Hatch timeline · todayPeak at 13:00
Hatch predictions
Today's headline hatch shown — see all 12 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
Top prey shown — see all 4 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
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.
- Marble trout carry a year-round no-take rule (reservoirs excepted); brown trout have a 25cm minimum size and a 1 Dec-second Saturday of Feb closed season; grayling a 33cm minimum and a 1 Jan-31 May closed season
- Individual concession-holders can extend or tighten these rules for their own stretch.
What's coming
Plan ahead
5-day outlook
Other water nearby · 4
Gallery · 2
Terrain map
The full read · show the working · for Grayling · confidence 90%
How the 87 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time90 × 13%11.7
Pressure80 × 7%5.6
Insect activity71 × 12%8.5
Conditions total= 87
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2026-02-15 → 2026-11-30
- Grayling 2026-06-01 → 2026-11-30
Rules are set at province or association level — check locally.
- Marble trout 2026-02-15 → 2026-11-30
Related guides
Booking & contacts
Rienza
Water temperature for Grayling
Ideal11.8°Cideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
June onward, holding up well into the back end of the season — the Rienza's grayling population is strong enough that it's worth planning a day specifically around them.
Where
Gravel runs and riffle heads through the middle valley, and the faster seams at the head of the longer glides lower down.
Method
Euro-nymph the faster water; switch to dries when the afternoon hatch shows on the flats.
Kit
10 ft #3 nymphing rod, 4-5 lb fluoro; 9 ft #4 for dries. 12 ft leader.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour.
Likely species
Mayflies
- Blue-winged oliveMost likely#16–18 · DunDuns are up; a sherry spinner fall may follow.
- Large dark oliveAlso possible#14–16 · EmergerDead-drift the emerger — it's sitting in the film.
- Turkey BrownAlso possibleLower confidence#14–16 · DunSmall spring dun on slower glides and margins.
- Ephemera vulgata (lake mayfly)Also possibleLower confidenceNearest relative#8–10–12 · NymphLarge lake/slow-river mayfly; burrows soft sediment.
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Net-spinning caddis (S. Europe)Also possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
- GrannomAlso possibleNearest relative#14–16 · PupaPupa first, then dries as the adults come off.
- Stone-case caddisAlso possibleLower confidenceNearest relative#14–16–18 · NymphTiny stone-cased larva; clean gravel riffles.
Stoneflies
- Little Brown StoneMost likelyLower confidence#16–18 · AdultSmall dark stone nymph or adult in early spring.
- NeedleflyAlso possibleLower confidenceNearest relative#16–18 · AdultSmall slender stonefly; clean, cold headwater riffles.
Hatch timeline · todayPeak at 13:00
Hatch predictions
Today's headline hatch shown — see all 12 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
Top prey shown — see all 4 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
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.
- Marble trout carry a year-round no-take rule (reservoirs excepted); brown trout have a 25cm minimum size and a 1 Dec-second Saturday of Feb closed season; grayling a 33cm minimum and a 1 Jan-31 May closed season
- Individual concession-holders can extend or tighten these rules for their own stretch.
What's coming
Plan ahead
5-day outlook
Other water nearby · 4
Gallery · 2
Terrain map
The full read · show the working · for Grayling · confidence 90%
How the 87 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time90 × 13%11.7
Pressure80 × 7%5.6
Insect activity71 × 12%8.5
Conditions total= 87
Can you trust it?
Water temperaturelive gauge readinggauge
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2026-02-15 → 2026-11-30
- Grayling 2026-06-01 → 2026-11-30
Rules are set at province or association level — check locally.
- Marble trout 2026-02-15 → 2026-11-30
Related guides
Booking & contacts