Freestone · Mixed · Primorsko-goranska / Gorski Kotar

Kupa (Upper / Risnjak NP)

Strict conservation fly fishery within Risnjak National Park — catch-and-release only, barbless hooks, no boats, no night fishing.

Marginal · Brown Trout
Large Dry Fly · 12-16
Marginallive now
Slow going — pick your moments
Low and clear — careful approach country. Cover and shadow are doing the work today.
90% confidence
What moved it
  • LevelModerate rain recentlyNo gauge reading
  • Water temp18.3°C
  • ClarityClear
Today’s fly
LD
Large Dry Fly12-16
Proven pattern for this period
Conditions on the water
Estimate
Level
Moderate rain recently
No gauge reading
Water temp18.3°C
ClarityClear
Weather26°C
WindE 9 km/h
Pressure1020 hPa
Rain · recent11.0 mm
Rain · ahead1.5 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Water temperature for brown trout
Warm — slow
18°C est.ideal 10–16°C
0°14°28°
How to fish it · for brown trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
⚠️ Water at 18.3°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots. Otherwise poor — water clarity is in the right range.
Hatch timeline · todayQuiet day

Hatch predictions

Today's headline hatch shown — see all 10 active hatches hour by hour with Pro.

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Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

Through the year
0–3 scale · July 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
GrannomHatch
2
2
Evening SedgeHatch
2
3
3
3
2
Large Dark OliveHatch
1
2
2
1
Iron BlueHatch
1
2
2
1

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Brown Trout fly box
LD
Large Dry FlyTop
12-16 · Pattern
Proven pattern for this period
Permits & access
Permit required — see local rules.
  • Croatian fishing licence plus local permit
  • Risnjak park section is catch-and-release, fly only, single barbless hook, no boats, and no night fishing
  • Park entrance also applies.
What's coming
Plan ahead
5-day outlook
Water here around 18°C. Nothing cooler within range — carry a thermometer.
About this water

Strict conservation fly fishery within Risnjak National Park — catch-and-release only, barbless hooks, no boats, no night fishing. The upper Kupa flows through dense Gorski Kotar forest with brown trout and grayling in classic upland freestone water. Good hatches of olives, caddis and stoneflies through spring and summer. Euro nymphing and dry fly both productive. Deeper stretches also hold huchen — strictly regulated trophy fishery in winter.

  • Mixed
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown

WFD classification · HRCSRN0481_001

The full read · show the working · for brown trout · confidence 90%
How the 38 is built — score × weight = contribution
Temperature51 × 28%14.3
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity56 × 12%6.7
Conditions total= 69
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Cooler water — back toward the 10–16 °C ideal band — would lift the score and ease welfare.
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Trout16 May → 30 September
  • Grayling16 May → 15 October
  • Hucho1 October → 28 February
Related guides
Hucho / Danube Salmonspecialist apex-predator guideGrayling Playbookgrayling tacticsEuro Nymphingsubsurface methods
Booking & contacts