Loch Drumbeg is a famous, large loch easily visible beside the B869 at Drumbeg. A beautiful location, there is a boat available and you can also fish much of the way around by bank. Although an easily accessible day's fishing, the far side from the road has lots of trees which can take a bit of negotiating. If on the boat try in and around the islands.
There are lots of trout, but they are mostly at the smaller end of the spectrum, but it can be prolific sport at times with top of the water action.