Spate · Mixed · West Wales / Carmarthenshire, GB-WLS

Cothi

A wide clear run of the River Cothi near Llwyn-y-ceiling in winter low water, with wooded valley sides and pale gravel banks.
Prime · Brown Trout
CDC Emerger · 16-18
Primelive now
About as good as it gets
River steady at a fishable height. On the feed top to bottom — start on the rises with a dry, drop a nymph if they stay down.
75% confidence
What moved it
  • Level0.46 mLast reading 20h ago
  • Water temp13.9°C
  • ClarityClear
Today's fly
CDC Emerger
CDC Emerger16-18
Upstream dry, in the film
Conditions on the water
Live gauge
Level
Steady
0.46 m
Last reading 20h ago
Water temp13.9°C
ClarityClear
Weather12°C
WindNE 9 km/h
Pressure1020 hPa
Rain · recent0.0 mm
Rain · ahead1.4 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
Ideal
14°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
Excellent — water temperature is working for you, but time of day is the limiting factor today.
Hatch timeline · todayPeak at 6am

Hatch predictions

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Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 4 guilds with Pro.

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Beyond the hatch · worth watchingambient prey

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Evidence
Survey-backed · regionalHigh confidence

Backed by regional invertebrate surveys; no sampling on this exact reach yet.

Through the year
0–3 scale · August highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Salmon runRun
1
2
2
2
2
2
1
Trout seasonSeason
1
2
2
2
2
2
1
Daddy Long LegsHatch
2
3
2
March BrownHatch
2
3
2
GrannomHatch
2
2
Large StoneflyHatch
2
3
2

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

Ranked for today
Brown Trout fly box
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Teifi
18 km
Brown trout · Salmon · Sea trout
Towy (Tywi)
19 km
Brown trout · Salmon · Sea trout
Amman
21 km
Brown trout · Sea trout · Salmon
Afon Llwchwr (Loughor)
28 km
0
Sea trout · Brown trout · Salmon
Afon Twrch
29 km
0
Brown trout
Gallery · 6
  1. A wide clear run of the River Cothi near Llwyn-y-ceiling in winter low water, with wooded valley sides and pale gravel banks.
    River Cothi near Llwyn-y-ceiling
  2. The River Cothi flowing through the village of Pumsaint in Carmarthenshire, tree-lined banks in autumn light.
    Afon Cothi in Pumsaint
  3. The Afon Cothi viewed from Pont Prenllwyd in October, autumnal wooded valley and fast-flowing water over boulders.
    Afon Cothi from Pont Prenllwyd
  4. The River Cothi at Pont-ar-gothi in spring, a broad calm glide with wooded banks and the old bridge behind.
    The River Cothi at Pont-ar-gothi
  5. Looking upstream along the Afon Cothi near Llanegwad in November, bare alders overhanging slow dark water.
    Afon Cothi near Llanegwad
  6. Terrain map of the venue
    Terrain map
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown
What this classification means

NRW WFD Cycle 3 — Cothi (confluence with Marlais to confluence with Tywi): Good ecological status; the lower Cothi sewin water. Corrected 2026-06-18 from a Clydach-tributary tag. Source: NRW DataMapWales WFD Cycle 3 classification layer.

NRW (Wales) · GB110060036300

The full read · show the working · for Brown Trout · confidence 75%
How the 81 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time40 × 13%5.2
Pressure80 × 7%5.6
Insect activity60 × 12%7.2
Conditions total= 81
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
The dawn and dusk windows score higher than the midday lull.
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon 1 April → 17 October
  • Trout 3 March → 30 September

Sea trout: Variable seasonal (2026) — Towy tributary rated At Risk by NRW. Sea trout present and fishable June–August but stocks share the wider Towy system decline. Night fishing after summer rain is the productive window; low clear water is unproductive.

Salmon: Negligible (2026) — NRW / EA 2024 Salmon Stocks Assessment classifies this Welsh principal salmon river 'at risk' — egg deposition below Conservation Limit. All Wales byelaws (in force 2020-2030) make catch & release mandatory. Conservation priority; not a salmon fishing destination. The Cothi is a Tywi tributary and shares its at-risk status.

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