Think of reservoir trout fishing, and you probably think of catching stocked rainbows. Rosebush Reservoir could not be further from that. This 30 acre lake, up in in the Preseli Hills, is not artificially stocked and holds a head of wild brown trout.

The previous evening’s reconnaissance of the River Cleddau had shown a great looking river, clouds of insect life, but disappointingly few trout rising. I decided to look elsewhere for my Bank Holiday wild brown trout hunt. The main fishing reservoir in Pembrokeshire, Llys y Frân, holds mainly Rainbow Trout, and has always been disappointing for me. Many childhood afternoons and evenings were spent here, failing to catch a thing. My thoughts turned towards the nearby, older reservoir: Rosebush.

The location of this upland lake could be the setting for an episode of the BBC’s Hinterland. The recently felled forest and sporadic bare trees (acid rain?) added to the desolation. In the fog, this can be a foreboding place. Today, however the forecast was for cloudless skies all day. The sun beat down on an empty lake, as I arrived at the boathouse. Inside, pinned to a board, was a list of Rosebush fly fishing members from 2014. It felt like no-one had visited this place in a couple of years.


Although, I saw strangely little insect life, the shallows were black with minnow fry. Maybe my fears over acid rain were unfounded. Something was thriving in the lake. A heron and a pair of grebes suggested a living could be found here.

Thousands of Minnow fry, Phoxinus phoxinus, shoaling in the shallows

We launched the aluminium boat, and headed for the shallower upstream arm of the lake. Taking the bright conditions into account, I opted for fishing deep with a sinking line and a team of three flies: A tungsten-headed hare’s ear black barbless on the point, a diawl bach on the dropper and a black zulu on the bob.

I’ve not fished from a metal rowing boat before. Noisy. Every movement, every pull of the oars, rang out a dull metallic clang. It must have been like a leper’s bell, scaring all the trout into hiding. Clang! Clunk! Thud! Not a fish was to be seen in the clear waters, other than an occasional jumping minnow.

We broke for lunch back on shore. A pair of red kite soared high above.

While I was waiting to re-embark, I tried a few short-range flicks from the bank. I still had on my sinking line, so the flies were snagging the weeds. On the second cast, I felt a slightly different resistance. Could it be….? I wound in to find a tiny trout hooked on the Diawl Bach.


A wild brown trout, Salmo trutta caught on a size 14 Diawl Bach Nymph

This is possibly the smallest fish I have ever caught, but it gave me pleasure out of all proportion to its size. A Welsh wild brown trout on a Welsh fly. I value this tiny catch higher than the 5lb+ rainbow trout earlier in the month.

To reduce snagging, I switched over to a floating line and tried a few different flies on the point, but couldn’t reproduce my surprise catch, either on the bank or back out on the boat.

I’ll return another time, when the sun is not so strong, and preferably in the evening. A pair of waders would be useful to work in the margins rather than get back in that metal boat.


Total Catch:

  • 1 Brown Trout (Diawl Bach)