Mountain Freestone · Volcanic · Honshū, JP

Azusa River (Kamikōchi)

Japan Alps river
Tomorrow · Not the day for it
Sculpin Streamer
Forecast · Tomorrow
Not the day for it
Not much stacked in your favour today. Worth an hour if you are nearby, not worth the special trip.
45% projected
Today's fly
Sculpin Streamer
Sculpin Streamer
Conditions on the water · Tomorrow
Estimate
Level
Very heavy rain recently
No gauge reading
Water temp12.6°C
ClarityUnfishable
Weather17°C
WindN 6 km/h
Pressure1026 hPa
Rain · recent57.6 mm
Rain · ahead16.7 mm

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

Water temperature for Rainbow Trout
Ideal
13°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
Poor — water temperature is working for you, but water clarity is the limiting factor today.
Hatch timeline · tomorrowPeak at 14:00

12:00(now) — Himalopsyche japonica

Stage: Taking dunsApproach: Dry flyActivity: 47%
Also:Daddy Long Legs45%Heather Fly45%Autumn Olive32%
Peak emergence windowWeather boost12 food groups active

Peak activity at 14:00 — Autumn Dun (Autumn Dun, Weather boost)

Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 as a supporter.

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Evidence
Records-basedModerate confidence

Based on species-occurrence records, not local invertebrate surveys.

Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Stenopsyche CaddisHatch
2
3
3
2
Cicada (Semi)Hatch
2
2
Ephemera strigata (Mid-Reach Keiryu Mayfly)Hatch
2
3
3
3
2
Epeorus latifolium (Riffle Mayfly)Hatch
2
3
3
3
3
3
2

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

Ranked for today
Fly box · Rainbow Trout
Permits & access
Permit required — see local rules.
  • Kamikōchi is protected; local co-operative rules and a yugyoken apply, with access and method limits
  • Confirm before fishing.
What's coming
Plan ahead
5-day outlook
Other water nearby · 2
Kiso River (upper / Kiso Valley)
50 km
20
White spotted char · Amago · Rainbow trout
Kurobe River (upper gorge)
33 km
White spotted char
Gallery · 2
  1. Japan Alps river
    Alpine river through UNESCO-protected Kamikōchi.
  2. Terrain map of the venue
    Terrain map
Conservation note

White-spotted char (iwana), yamame, and stocked rainbow. Iwana and yamame are the wild natives.

The full read · show the working · for Rainbow Trout · confidence 55%
How the 20 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow40 × 22%8.8
Clarity10 × 18%1.8
Feeding Time60 × 13%7.8
Pressure75 × 7%5.3
Insect activity64 × 12%7.7
Limiting factor: Water is unfishable — too coloured for Rainbow Trout= 59
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
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
Apple MapsGoogle Maps
Seasons & zones
  • Char late February to April → late September to mid-October

    Honshu/Shikoku/Kyushu keiryu are managed by local fishery co-operatives — a yugyoken (day/annual ticket) is required, and most streams close around 30 September / mid-October for spawning. Species are surfaced in prose only (no engine slugs for yamame, amago or iwana). Legal status: guidance_not_permission.

Related guides
Euro Nymphingsubsurface methods
Booking & contacts