Llyn Aled Isaf is a long and shallow reservoir near Llyn Aled Uchaf. It is not stocked. It is located on the bleak Denbigh moors. Fish present include pike, perch, roach and a few brown trout. it is primarily considered a coarse fishery. All methods are allowed. Fishing is £15 a day, with the permit avavaible through Welsh Water at Llyn Brenig visitor center or through the Welsh Water website.