Spate · Mixed · South Wales / Cardiff / Caerphilly, GB-WLS

River Rhymney

The River Rhymney flowing past Bedwas in South Wales, a gently curving rural river stretch bordered by trees.

Down the Rhymney Valley from the head of the South Wales coalfield through Bedwas and the eastern Cardiff suburbs to the Severn estuary.

Prime · Sea Trout
Black & Silver Tube · 1-2 inch
Primelive now
Prime conditions — go now
Low and clear — careful approach country. Cover the water properly, fish each lie once.
90% confidence
What moved it
  • Level0.18 m
  • Water temp12.4°C
  • ClarityClear
Today's fly
BS
Black & Silver Tube1-2 inch
In deep pools and dark water, silhouette and contrast do the work colour cannot. A fly that reads as black against depth is enough. Fish it broadside, hold the swing, let it hang at the dangle — that is when the best fish take.
Conditions on the water
Live gauge
Level
Steady
0.18 m
Water temp12.4°C
ClarityClear
Weather10°C
WindN 11 km/h
Pressure1025 hPa
Rain · recent0.1 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 Sea Trout
Ideal
12°C est.ideal 8–15°C
0°14°28°
How to fish it · for Sea Trout
When
August through September — autumn lifts only. Night work once water reaches 13°C. All-Wales At Risk plus urban-recovery context — catch-and-release as a binding ethic.
Where
Lower Rhymney pool tails above the tidal limit at Cardiff. Walk the beat in daylight.
Method
Small wets — size 10 to 12 Medicine, Peter Ross, Teal Blue and Silver — across-and-down on a floating line. On falling water carry a sink-tip for the deeper pots. Fish methodically from the tail of each pool; the take comes on the swing.
Kit
9 to 10 ft #6/7, floating line plus a light sink-tip in the bag. 8 to 10 lb fluoro. The river is small enough to wade carefully between casting positions.
Why this works
Excellent — water temperature is right today, though insect activity could be better. ⏰ Sea trout become most active after dark, but this stretch closes at 19:58 — before that window fully opens. Fish hard in the last legal hour: overcast skies and warm evenings can bring fish on early even in fading light.
Hatch timeline · todayPeak at 6am

Hatch predictions

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Sub-surface · on the nymphunder the surface

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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
1
Sea trout runRun
1
2
2
2
2
2
2
1
Trout seasonSeason
1
2
2
2
2
2
1
March BrownHatch
2
3
2
CapererHatch
2
3
3
2
Heather FlyHatch
2
2
Autumn DunHatch
2
3
2

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

Ranked for today
Sea Trout fly box

Wild-river first principles. Early-season nymphs and practical searching, then dry flies, emergers and spiders as hatches and surface activity improve.

BS
Black & Silver TubeTop
1-2 inch · Tube
In deep pools and dark water, silhouette and contrast do the work colour cannot. A fly that reads as black against depth is enough. Fish it broadside, hold the swing, let it hang at the dangle — that is when the best fish take.
SF
Snake Fly (Black)
2-4 inch · Streamer
A mobile eel-like profile that undulates through deep pools — effective when sea trout are lying deep and not responding to conventional wets.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
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11 km
80
Brown trout · Grayling · Salmon
Rhondda
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Brown trout · Grayling · Salmon
Bargoed Park
12 km
Brown trout · Rainbow trout
Gallery · 2
  1. The River Rhymney flowing past Bedwas in South Wales, a gently curving rural river stretch bordered by trees.
    The River Rhymney at Bedwas, South Wales, looking west along a quiet rural stretch.
  2. Terrain map of the venue
    Terrain map
About this water

Down the Rhymney Valley from the head of the South Wales coalfield through Bedwas and the eastern Cardiff suburbs to the Severn estuary. Another industrial-recovery story — wild brown trout through the middle valley, sewin on the autumn lifts, the salmon side a genuine rumour rather than a fishery. Like its neighbours the Taff and Ely, the Rhymney is more interesting than its postcode would suggest, and the recovery work continues.

  • Mixed
Water quality (WFD)
  • Ecology: Good
  • Chemical: Unknown
What this classification means

NRW WFD Cycle 3 — Rhymney (conf Nant Cylla to Chapel Wood, Bedwas): Good ecological status. Corrected 2026-06-18 from a Nant-Glandulas tributary tag (was recorded Moderate). Source: NRW DataMapWales WFD Cycle 3 classification layer.

EA (England) · GB109057027280

Why this score · for Sea Trout
  • Temperature10028% weight
  • Flow8022% weight
  • Clarity8518% weight
  • Feeding Time8013% weight
  • Pressure857% weight
  • Insect activity5612% weight
Directions
Apple MapsGoogle Maps
Seasons & zones
  • Salmon 1 May → 17 October
  • Sea trout 3 March → 17 October
  • Trout 3 March → 30 September

Sea trout: Variable seasonal (2026) — Recovering industrial valley river; sewin work up on autumn lifts in modest numbers. All-Wales At Risk picture applies. The Rhymney's value as a fishery is in its recovery, not in destination angling.

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