Freestone · Volcanic · Hokkaido

Akan River

Akan Riv 1
Marginal · Rainbow Trout
Foam beetle / hopper · 10-14
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 temp18.6°C
  • ClarityClear
Today's fly
Foam beetle / hopper
Foam beetle / hopper10-14
Proven pattern for this period
Conditions on the water
Estimate
Level
Moderate rain recently
No gauge reading
Water temp18.6°C
ClarityClear
Weather17°C
WindSW 12 km/h
Pressure1016 hPa
Rain · recent13.9 mm
Rain · ahead0.0 mm

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

Water temperature for Rainbow Trout
Warm — slow
19°C est.ideal 10–18°C
0°14°28°
How to fish it · for Rainbow 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 18.6°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 6pm

Hatch predictions

Today's headline hatch shown — see all 9 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 2 guilds 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
Stenopsyche CaddisHatch
2
3
3
2
Cicada (Semi)Hatch
2
2
GrannomHatch
2
2
Evening SedgeHatch
2
3
3
3
2

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

Ranked for today
Rainbow Trout fly box
Permits & access
Permit required — see local rules.
  • Managed C&R/charge zone near the lake outflow — confirm payment, permitted reach and hook rules.
What's coming
Plan ahead
5-day outlook
Water here around 19°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. Akan Riv 1
    River draining Lake Akan.
  2. Terrain map of the venue
    Terrain map
Conservation note

Rainbow trout and white-spotted char (amemasu). Lead with the managed catch-and-release upper reach.

The full read · show the working · for Rainbow Trout · confidence 90%
How the 36 is built — score × weight = contribution
Temperature81 × 28%22.7
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time60 × 13%7.8
Pressure75 × 7%5.3
Insect activity59 × 12%7.1
Conditions total= 76
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Char spring → late autumn

    Hokkaido is largely open-access for inland trout/char, with managed/charged zones the exception (e.g. the Akan C&R water). Verify the exact reach. Species surfaced in prose only. Legal status: guidance_not_permission.

Related guides
Euro Nymphingsubsurface methods
Booking & contacts