Mayflies
Stoneflies
Caddisflies
Damselflies & dragonflies
- Ecology: Good
- Chemical: Unknown
WFD classification · FRFRR245_3
Rules at a glance
- Day tickets
- Fly only
Water temperature for Grayling
Ideal10°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn — September through October prime in this high-altitude tributary. Grayling are present but sparse.
Where
Slower glides in the lower Marcadau where the gradient eases. Above the steeper sections is brown-trout-only pocket water.
Method
Euro-nymphing through the slower pockets; dries on autumn afternoons when the air warms.
Kit
10 ft #3 nymphing rod for the deep pockets; 9 ft #4 for dries. 4 to 5 lb fluoro tippet, 12 ft leader.
Likely species
Hatch timeline · todayPeak at 12:00
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
Supporters see the full sub-surface read.
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
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October 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
1
Alpine RhithrogenaHatch
2
3
3
2
Sculpin / Baitfish (Rivers)Hatch
2
3
3
3
3
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
Hook 14–18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- AAPPMA permits
- Fly-only sections common in Pyrenees.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Cauterets, vallee du Marcadau Terrain map
Water quality (WFD)
The full read · show the working · for Grayling · confidence 75%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow60 × 22%13.2
Clarity85 × 18%15.3
Feeding Time95 × 13%12.4
Pressure80 × 7%5.6
Insect activity48 × 12%5.8
Conditions total= 80
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2.º Saturday de March → 3.º Sunday de September
- Grayling 3.º Saturday de May → 3.º Sunday de September
France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.
Related guides
Booking & contacts
Gave du Marcadau
Water temperature for Grayling
Ideal10°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Autumn — September through October prime in this high-altitude tributary. Grayling are present but sparse.
Where
Slower glides in the lower Marcadau where the gradient eases. Above the steeper sections is brown-trout-only pocket water.
Method
Euro-nymphing through the slower pockets; dries on autumn afternoons when the air warms.
Kit
10 ft #3 nymphing rod for the deep pockets; 9 ft #4 for dries. 4 to 5 lb fluoro tippet, 12 ft leader.
Likely species
Hatch timeline · todayPeak at 12:00
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
Supporters see the full sub-surface read.
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
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October 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
1
Alpine RhithrogenaHatch
2
3
3
2
Sculpin / Baitfish (Rivers)Hatch
2
3
3
3
3
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
Hook 14–18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- AAPPMA permits
- Fly-only sections common in Pyrenees.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Cauterets, vallee du Marcadau Terrain map
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · FRFRR245_3
The full read · show the working · for Grayling · confidence 75%
How the 0 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow60 × 22%13.2
Clarity85 × 18%15.3
Feeding Time95 × 13%12.4
Pressure80 × 7%5.6
Insect activity48 × 12%5.8
Conditions total= 80
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
Directions
Seasons & zones
- Trout 2.º Saturday de March → 3.º Sunday de September
- Grayling 3.º Saturday de May → 3.º Sunday de September
France national rule: grayling opens 3rd Saturday of May in all waters. In 1st category (salmonid) rivers, grayling closes with the trout season on the 3rd Sunday of September. Departmental regulations may impose additional restrictions. Always check the relevant département's 2026 arrêté préfectoral.
Related guides
Booking & contacts