Freestone · Sedimentary · Shikoku

Shimanto River

Spring in Shimanto River
Poor · Amago
Tenkara kebari (reverse-hackle) · 12–16
Poorlive now
Not the day for it
Low and clear — careful approach country. A morning for the obvious fish only.
90% confidence
What moved it
  • LevelLight rain recentlyNo gauge reading
  • Water temp20.0°C
  • ClarityClear
Today's fly
Tenkara kebari (reverse-hackle)
Tenkara kebari (reverse-hackle)12–16
A dependable searching pattern for these waters.
Conditions on the water
Estimate
Level
Light rain recently
No gauge reading
Water temp20.0°C
ClarityClear
Weather21°C
WindE 5 km/h
Pressure1010 hPa
Rain · recent4.3 mm
Rain · ahead6.1 mm

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

Water temperature for Amago
Warm — slow
20°C est.ideal 9–17°C
0°14°28°
How to fish it · for Amago
When
Spring to the autumn closure (salmonids in the upper river)
Where
The Shimanto is called Japan's last clear river — a long, undammed, gently flowing water through rural Kōchi crossed by its famous low 'sinking bridges',…
Why this works
Water at 20°C. This is the line where catch-and-release kills masu salmon. Do not fish for them today.
Hatch timeline · todayPeak at 6pm

Hatch predictions

Today's headline hatch shown — see all 12 active hatches hour by hour with Pro.

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Sub-surface · on the nymphunder the surface

Hatch predictions

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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
Amago fly box
EH
Elk Hair / Stenopsyche caddis
12–14 · Sedge
Evening sedge — twitch or dead-drift it as the light goes.
CB
Cicada & beetle terrestrials (midsummer)
10–12 · Terrestrial
Fish it tight to the bank on warm, breezy days.
Permits & access
Permit required — see local rules.
  • Co-operative yugyoken required; ayu and salmonid rules differ; spawning closure in autumn
  • Confirm the exact reach.
What's coming
Plan ahead
5-day outlook
Water here around 20°C. Nothing cooler within range — carry a thermometer.
Gallery · 2
  1. Spring in Shimanto River
    Japan's longest free-flowing river.
  2. Terrain map of the venue
    Terrain map
Conservation note

White-spotted char (iwana) and amago in the upper reaches (ayu in the lower river).

The full read · show the working · for Amago · confidence 90%
How the 10 is built — score × weight = contribution
Temperature33 × 28%9.2
Flow60 × 22%13.2
Clarity95 × 18%17.1
Feeding Time25 × 13%3.3
Pressure80 × 7%5.6
Insect activity64 × 12%7.7
Conditions total= 56
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 9–17 °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
  • 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