Caddisflies
Gammarids
- Ecology: Moderate
- Chemical: Failing to achieve good
WFD classification · CZHVL_1250
Rules at a glance
- Licence required
Water temperature for Grayling
Ideal13°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
Poor — water temperature is working for you, but river flow is the limiting factor today.
Likely species
Caddisflies
- Large sedgesMost likelyNearest relative#8–10 · AdultBig waked sedge in the last light and after dark.
- Green SedgeAlso possibleLower 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.
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 · regionalModerate 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
Trout seasonSeason
1
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Autumn OliveHatch
1
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.
- State licence + local permit
- Multiple quality sections with fly-only rule
- Brown trout protected Sep 1–Apr 15
- Grayling protected Dec 1–Jun 15.
What's coming
Plan ahead
5-day outlook
Fishing better nearby · 5
Gallery · 2
File:View to Písek from Otava River (1).JPG Terrain map
Water quality (WFD)
The full read · show the working · for Grayling · confidence 50%
How the 30 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow15 × 22%3.3
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity26 × 12%3.1
Limiting factor: River is stable — Grayling prefers medium flow= 63
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
A drop and clear would lift the flow and clarity scores.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 16 April → 31 August
- Grayling 16 June → 30 November
Czech national rule: grayling (lipan podhorní) protected 1 December – 15 June. Open window is 16 June – 30 November. Czech Anglers Union (ČRS) salmonid fisheries also have method and access rules — check the local ČRS district permit for specific conditions.
Closed in spring for spawning.
Prime sport 1 September → 30 November
Related guides
Booking & contacts
Otava
Water temperature for Grayling
Ideal13°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
Poor — water temperature is working for you, but river flow is the limiting factor today.
Likely species
Caddisflies
- Large sedgesMost likelyNearest relative#8–10 · AdultBig waked sedge in the last light and after dark.
- Green SedgeAlso possibleLower 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.
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 · regionalModerate 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
Trout seasonSeason
1
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Blue Winged OliveHatch
1
2
2
2
2
1
Autumn OliveHatch
1
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.
- State licence + local permit
- Multiple quality sections with fly-only rule
- Brown trout protected Sep 1–Apr 15
- Grayling protected Dec 1–Jun 15.
What's coming
Plan ahead
5-day outlook
Fishing better nearby · 5
Gallery · 2
File:View to Písek from Otava River (1).JPG Terrain map
Water quality (WFD)
- Ecology: Moderate
- Chemical: Failing to achieve good
WFD classification · CZHVL_1250
The full read · show the working · for Grayling · confidence 50%
How the 30 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow15 × 22%3.3
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity26 × 12%3.1
Limiting factor: River is stable — Grayling prefers medium flow= 63
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
A drop and clear would lift the flow and clarity scores.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
- Trout 16 April → 31 August
- Grayling 16 June → 30 November
Czech national rule: grayling (lipan podhorní) protected 1 December – 15 June. Open window is 16 June – 30 November. Czech Anglers Union (ČRS) salmonid fisheries also have method and access rules — check the local ČRS district permit for specific conditions.
Closed in spring for spawning.
Prime sport 1 September → 30 November
Related guides
Booking & contacts