This lough lies immediately north of Finlough to the west of the L101. It lies at the foot of the Sheeffry Hills to the east and the Mweelrea Mountains to the west. In fact, Mweelrea rises so steeply that it casts a shadow across the lough from early afternoon – something I found doesn’t do the fishing any harm at all. The lough gets a run of spring salmon, some grilse and a good run of sea trout.
Like Finlough, it was one of the fisheries on Kingmill Moore’s itinerary and he talks of sea trout of up to 10 lb being taken. It can still produce a memorable day’s fishing and the 1985 season saw one bag of 40 sea trout to 5½ lb and a 12 lb salmon. The lough fishes best for spring salmon in March and April – the east shore along by the boat quay and up to Fisherman's Point is a favourite drift. The sea trout fishing begins in earnest in July, though some really big fish come in from April.
The whole southern part of the lough can yield a fish even well out from the shore, and also the west shore from the ‘Split Rock’ right to the top as well as around the islands towards the roadside. All the usual sea trout flies work well, but I have a particular preference for the Delphi, the Daddy, Jacob’s Ladder, Black Doctor and the Kingsmill. One day they want them small, the next day big – even on a size 6 hook! Because of its location deep among the mountains, Doo Lough can be treacherous in windy weather and it is well to get off it before the storm blows up to lift sheets of water and anything else in its way up into the grey sky.
Excerpts taken from "Trout & Salmon Rivers of Ireland, an angler's guide" by Peter O'Reilly.