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
River temperature is the limiting factor today, not the flow. Fish dawn or dusk if you go at all, and handle everything with extra care.
80% confidence
What moved it
  • Level0.47 mLast reading 19h ago
  • Water temp19.9°C
  • ClarityClear
Today's fly
LD
Large Dry Fly12-16
Proven pattern for this period
Conditions on the water
Live gauge
Level
Steady
0.47 m
Last reading 19h ago
Water temp19.9°C
ClarityClear
Weather23°C
WindNE 19 km/h
Pressure1023 hPa
Rain · recent0.0 mm
Rain · ahead0.0 mm

The nearest gauge doesn't record temperatures, so we've estimated it — defer to the river keeper's advice.

Water temperature for Brown Trout
Warm — slow
20°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 19.9°C — above the brown trout caution line (18°C). Fish dawn or dusk only. Land it fast, wet hands, no air shots.
Hatch timeline · todayPeak at 6am

Hatch predictions

Today's headline hatch shown — see all 4 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

See the full sub-surface read with Pro.

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Beyond the hatch · worth watchingambient prey

Hatch predictions

Top prey shown — see all 2 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 · August 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

Best represented by the Gacka and similar waters: clear, stable limestone rivers where dry fly, nymph and streamer all matter.

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 20°C. Nothing cooler within range — carry a thermometer.
Gallery · 1
  1. Kupa (Risnjak National Park) — IMG 20180713 163857(fixed)
    IMG 20180713 163857(fixed)
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 80%
How the 28 is built — score × weight = contribution
Temperature26 × 28%7.3
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time60 × 13%7.8
Pressure80 × 7%5.6
Insect activity64 × 12%7.7
Conditions total= 63
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
  • Trout 16 May → 30 September
  • Grayling 16 May → 15 October

    Conflicting sources for Kupa grayling season: Risnjak National Park (upper Kupa, C&R) lists grayling 16 May – 15 October; Kupa Fly Fishing operator lists 1 April – 15 October. Use the stricter May window until the specific beat/concession confirms otherwise. Croatian national rule: one rod, artificial fly or lure only in permanent grayling habitats.

    Prime sport 1 August → 15 October

    • 16 May → 15 Oct · Artificial fly or artificial lure
  • Hucho 1 October → 28 February
Related guides
Hucho / Danube Salmonspecialist apex-predator guideGrayling Playbookgrayling tacticsEuro Nymphingsubsurface methods
Booking & contacts