Wild brown trout with some stocking. Very flashy after rain when the slate geology drains fast.
- Slate
Rules at a glance
- Day tickets
Water temperature for Grayling
Cool — slow3°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
Good — water clarity is right today, though water temperature could be better.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 3 guilds 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 · November highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
March BrownHatch
2
3
2
Late March BrownHatch
2
3
2
Large Brook DunHatch
2
3
2
Large StoneflyHatch
2
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Grayling fly box
A proper Ardennes river-trout pack for Wallonia, centred on clear to lightly coloured rivers with trout and some classic fly-fishing culture.
Hook 14–18 · Fly
in season
Permits & access
Permit required — see local rules.
- Permis de pêche (Wallonia) / Visverlof (Flanders)
- Foreign anglers can purchase online or at post offices without residency.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
About this water
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · BERW06_AM05R
The full read · show the working · for Grayling · confidence 70%
How the 66 is built — score × weight = contribution
Temperature49 × 28%13.7
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity50 × 12%6.0
Conditions total= 66
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Warcheproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Warmer water — toward the 4–14 °C ideal band — would lift the temperature score.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 3rd Saturday of March → 30 September
Related guides
Booking & contacts
Holzwarche
Small Ardennes tributary near the German border—intimate trout water with pocket water and short drifts perfect for a tight line.
Water temperature for Grayling
Cool — slow3°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
Good — water clarity is right today, though water temperature could be better.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 3 guilds 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 · November highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
March BrownHatch
2
3
2
Late March BrownHatch
2
3
2
Large Brook DunHatch
2
3
2
Large StoneflyHatch
2
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Grayling fly box
A proper Ardennes river-trout pack for Wallonia, centred on clear to lightly coloured rivers with trout and some classic fly-fishing culture.
Hook 14–18 · Fly
in season
Permits & access
Permit required — see local rules.
- Permis de pêche (Wallonia) / Visverlof (Flanders)
- Foreign anglers can purchase online or at post offices without residency.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
About this water
Wild brown trout with some stocking. Very flashy after rain when the slate geology drains fast.
- Slate
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · BERW06_AM05R
The full read · show the working · for Grayling · confidence 70%
How the 66 is built — score × weight = contribution
Temperature49 × 28%13.7
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity50 × 12%6.0
Conditions total= 66
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Warcheproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Warmer water — toward the 4–14 °C ideal band — would lift the temperature score.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 3rd Saturday of March → 30 September
Related guides
Booking & contacts
At a glance
Holzwarche is a spate river in Wallonia / East Belgium. The catchment geology is recorded as slate, and the water sits at about 572 m above sea level. Species listed for this water: brown trout and grayling. The trout season is recorded as running from 3rd Saturday of March to 30 September. Best window recorded for anglers: Trout: 3rd Saturday of March – 30 September (Wallonia); Grayling: 1 June – 28 February (Wallonia). Core methods listed: Nymph; Dry fly; Wet fly / soft hackle. Its Water Framework Directive ecological status is recorded as good. Nearby waters in our listings include Lake Bütgenbach at 1.0 km, Lake Robertville at 7.0 km and Warche at 14 km.