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Sea trout, known in Wales as sewin are often called the fish of the night, yet they can be taken in daylight too. These silver travellers are brown trout that go to sea before returning to their home rivers. Wales is rightly famous for them, with the Towy, Teifi, Dovey, and Dee offering some of the best sea trout fishing in the British Isles.

Where to Fish

River Towy

Perhaps the most famous Welsh sea trout river, the Towy in Carmarthenshire produces some of the biggest fish each season. Classic night water with steady glides and deeper pools.

River Teifi

The “Queen of Welsh Rivers” has wonderfully varied water. Night fishing shines around Cenarth and Llandysul, with fish spreading through the system on summer freshets.

River Dovey (Dyfi)

A true spate river that fishes best after rain. Smaller in scale than the Towy or Teifi, but consistent runs and lively sport.

River Dee

Better known for salmon, yet sea trout also run the Dee. Selected beats give rewarding summer fishing, especially when levels are up and the light is low.

Best Time of Year

Main runs arrive from late spring through to autumn. June, July and August are prime months for night fishing on settled, warm evenings. Fresh smaller fish often appear first, with larger fish arriving as the season progresses.

Night Fishing Tactics

• Stealth first: Enter the water quietly, keep wading to a minimum, and work down a pool with tidy casts.
• Across and down: Present the fly on a downstream arc and use a slow figure of eight retrieve. Listen for the swirl.
• Pool rotation: Take a short break after moving a fish; a change of fly or angle often converts a pluck into a solid take.

Daytime Fishing Tactics

Although famed as a fish of darkness, sea trout can be caught by day, especially in coloured or rising water and soon after fresh fish enter from the tide.

• Cover water: Work likely lies and heads of pools, plus broken water and seams where fish rest on a spate.
• Nymphs and small wets: Dead drift or swing a size 10 to 14 wet or nymph through riffles and tails.
• Streamers in spate: In rising water, short line a small zonker or muddler through pockets and margins.
• Light and leaders: Use a longer leader and fine tippet in clear water. When the light is low or the river has colour, step up in diameter.
• Watch the weather: The first push of water after rain can be golden. Fish actively as new arrivals move fast.

Flies and Materials

Traditional Welsh patterns use natural feathers, classic dubbing, and strong threads and tinsels. Modern twists add synthetic materials for flash and durability. Choose quality hooks with reliable wire strength for powerful fish.

Night Flies

• Teal Blue and Silver: Teal wing slips over a silver body for presence and shine. Materials: teal flank feathers, flat silver tinsel, black thread.
• Mallard and Claret: A Welsh favourite with a rich claret body and bronze mallard wing. Materials: dyed claret dubbing, bronze mallard feathers, fine gold wire.
• Black Pennell: Spare and effective when fish are shy. Materials: black dubbing or floss, soft black cock or hen hackle.
• Snake Fly: Articulated streamer for larger fish on dark nights. Materials: rabbit zonker strips, strong articulated hooks, flat waxed thread.

Daytime Flies

• March Brown (wet): A natural impression that works in coloured water. Materials: brown partridge hackle, hare’s mask dubbing, brown thread.
• Hare’s Ear Nymph: A banker on riffles and tails. Materials: hare’s ear dubbing, fine copper wire, soft hen hackle if you like a soft hackle collar.
• Silver Stoat (scaled down): Salmon heritage, sea trout approved. Materials: black cock hackle, silver tinsel, squirrel fur.
• Mini Zonker or Muddler: Pocket water searcher after a spate. Materials: rabbit fur, deer hair for a buoyant head, optional flash.

Final Thoughts

Whether you are swinging a teal and silver through a moonlit glide on the Teifi, or dropping a small nymph into the head of a Dovey pool as the river rises, Welsh sea trout reward care, patience and tidy presentation. The thrill of that sudden, heavy take — by night or by day — is hard to beat.