This is a 900 acre wild brown trout fishery. There is access on the north bank along a rough track, suitable for a 4 x 4. Otherwise most of the reservoir requires a good walk to access.

The fish average about 10oz but can run over 1lb. It is well known for its fall of coch-y-bonddu beetles in June, which can bring hundreds of fish to the surface to feed.

It is a good venue for fishing ‘walk and cast’ with a team of traditional wet flies. Fly fishing only is permitted.

The day ticket for Claerwen also includes the Claerwen river and several remote natural lakes within the catchment. Tickets are available from Hafod Hardware store, Daisy Powell newsagents in Rhayader or the Elan valley visitor centre.